how to make a ball mill gold ores

how much the gold ore ball mill - jxsc machine

how much the gold ore ball mill - jxsc machine

Capacity 0.65~130 t/h Feeding size 20-25mm Discharge size 0.074-0.89mm Grinding ball 1.5-338t Application gold ore and other ores grinding Advantages Rolling bearing has little friction and low consumption; Reasonable sealing, low failure; Little dust, low noise, energy-saving; Special design, good grinding effect, 60s manual response, 24hrs quotation. More ball mill model details

Since most of the gold mines contain impurities, we only can obtain the gold concentrate after a series of steps such as crushing, grinding, and sieving. The ball mill plays an important role in the gold ore grinding process, as a kind of high-efficiency fine grinding equipment, it has been widely used in fine grinding and ultra-fine grinding operations in mining, chemical, new materials, building materials and other fields. In the gold mining plant, the ball mill usually set after the jaw crusher, in a second-stage grinding, process sulfur-containing arsenic-containing refractory gold ore, and tailings treatment. The outstanding advantages of gold ball mill are low energy consumption, ultra-fine grinding, simple foundation, low noise and vibration, and has been regarded as an efficient new fine grinding equipment.

The main parts of the gold ore ball mill includes the feeding, the supporting device, the rotating part, the unloading device and the transmission device. Working principle: gold ore ball mill is a low-speed rotary cylinder horizontally mounted on the bearing. In the rotary cylinder, there are heavy steel balls. Along the motor and gear rotates the cylinder, generating centrifugal force to bring the steel ball to a certain height and then falling. The ore material are gradually crushed and ground by the steel ball impact force. The material is subjected to impact crushing and grinding, and the material is slowly flowed from the feeding end to the discharging end by the material level difference, until the material is discharged. That is the overflow ball mill.

Gold ore ball mill is especially suitable for two-stage grinding or ultra-fine grinding because of its advantages of ultra-fine grinding, high efficiency and energy-saving, low installation cost and low wear.

A gold mine used the JXSC gold ore ball mill for the second stage grinding to technically transform the original process, and achieved good results. After the transformation, the production capacity reached 130~140t/d. The production results show that the JXSC gold mine ball mill has low electromechanical consumption, high grinding efficiency, low wear of wearing parts and vibration noise less than 85dB.

There are rich sulfur-bearing and arsenic-containing refractory gold ore resources, but due to the lack of practical technology, these gold resources are not fully utilized. The JXSC Gold Mining Ball Mill has two basic characteristics of ultra-fine grinding and enhanced chemical leaching. The use of ultra-fine grinding of the JXSC gold ore ball mill can strengthen the alkali leaching, which may provide a technically feasible and economically reasonable treatment process for some sulfur-containing and arsenic-containing refractory gold ores.

Ball mill superfine grinding for secondary utilization of gold-bearing tailings in which gold was not fully recovered in the old days due to the technique limitation. In some gold tailings, the gold content is as high as 2~8g/t, if using the JXSC gold ore ball mill to retreat and recover gold, its potential economic benefits are huge.

The ball mill price are determined by many factors, such as machine weight, cylinder material, steel ball material, motor brand, lined plate thickness and material, etc. A professional and reasonable quotation made on your mine conditions, mine minerals, capacity, rock hardness, clay, etc. We are here to help.

JXSC is a 35 years Chinese mining equipment manufacturer, has great quality & price advantages in the ball mill, jaw crusher, trommel scrubber, shaker table and so on. Contact us for a 12hrs quotation.

determine the proper grind size for gold ore

determine the proper grind size for gold ore

Without mineralogy, estimating the optimumGrind Size for Gold Ore Sample is most conveniently made by Laboratory Testing and the agitation leaching method, and it will be necessary to make up 3 or 4 bottle charges in order to have enough ore* for the subsequent screen analysis.

Take an average sample of the ore and grind on the bucking table to pass No. 30 sieve. Weigh up 4 lots of 300 grams each and place in 4 standard acid bottles, add to each the quantity of lime estimated from the alkali consumption test, and water in the ratio of 3:1. For addition of cyanide it is best to make up a concentrated cyanide solution and ascertain the strength by titration. The number of cc equivalent to a given weight of cyanide may then be run in to the charge of ore and water in the bottle from a burrette. The volume of liquor to be so added may be allowed for when diluting the pulp, so as to give the exact ratio of solution to ore originally decided on. It is usually advisableto shake up the bottle containing the ore water and lime before adding the cyanide.

Add sufficient cyanide to make a solution strength of 0.3 % KCN, stopper the bottles securely, and place in the agitating wheel. For the purpose of this test it is well to give an agitation period of 6 or 7 days. Treatment of sand by agitation will usually give the same result as by leaching, only in less than half the time. For the first 3 days of agitation (and longer if the cyanide consumption continues to any considerable extent), open the bottle each day and test 10 cc of the solution for cyanide and alkali. If necessary add lime and cyanide sufficient to maintain alkalinity between 0.05 and 0.1, and cyanide at 0.3% KCN.

Some metallurgists prefer to add a given amount of cyanide and let the experiment run the full time of treatment without testing and maintaining the cyanide strength. This does not seem to have anything to recommend it, and is at variance with normal working conditions, because it is usual in practice to maintain the cyanide strength at a definite figure for all or the greater part of the time of treatment. Moreover, it may often happen in making a bottle test on an unknown ore that the whole of the cyanide added at the start may be consumed long before the time of treatment is up, and the fact is not known till the end, resulting in a useless experiment and wasted time.

At the end of the period the solution is titrated and consumption of cyanide calculated, but the result thus shown should not be used for basing working figures upon. The charge is then washed, either on a laboratory filter or by decantation. In the latter case the four charges may be combined in an enamelled bucket, and settled, decanted, and washed, as one sample. The whole is afterward dried, and 1000 grams weighed up for screen analysis, while a sample of the remainder is assayed as a check.

A convenient screen series for the sizing will be Nos. 40, 60, 80, 100, 150, and 200, or if the Tyler Standard screens be used, 35, 48, 65, 80, 100, 150, and 200. If desired the 200 product may befurther separated into granular and colloidal matter by panning, though such a division made by this means is arbitrary, and results obtained by different operators are not comparable.

For the screen analysis it is often more satisfactory first to separate out the colloidal matter by panning and then dry the granular part before screen sizing. Another plan is to remove the colloids and the finest of the sand by washing them into a bucket through a No. 200 sieve under the water tap. The two products are then dried separately, and the oversize graded in the usual way. In this case there will probably be some 200 sand left in the original oversize which may be screened out dry and added to that which was washed through the sieve with water.

Some metallurgists prefer to do the whole of the screen-sizing in water, and this has the advantage of avoiding any possible error due to decrepitation of the larger particles in drying, but such a risk is small when the drying is conducted at a low temperature; moreover, water screening takes longer to attain the ultimate limit of separation between each grade, and there is a danger of stopping the operation before it is complete.

In dry screening the common practice of putting a washer on the screen or rubbing the pulp on it with a block of wood is not to be recommended, because it forces through the meshes particles which would not otherwise pass, giving a higher reading for the minus product than the correct one, and incidentally it displaces the wires making the mesh irregular and soon impairing the standard quality of the screens besides materially shortening their life. The main incentive to this practice is the difficulty often experienced through blinding of the meshes by the clayey matter in the ore. For this reason it is recommended that the colloids be first removed by water washing, but if it is found necessary or advisable to dry-screen a sample entire, the meshes may be kept free from the fine slime by continually tapping sharply on the top edge of the sieve with the handle of a spatula or other similar instrument, and in this way good time may be made even on very colloidal material.

In the case of ground pulp that has been wet and subsequently dried, however, this method is not satisfactory as the colloidal part in drying forms hard pellets or granules which remain on the screens,and are recorded as sand. In such cases in order to obtain reliable results the dry pulp should be thoroughly disintegrated in water and the colloids floated off before the screen test is made. If a known quantity of the dry pulp be first weighed up the sample after disintegration in water may be washed on the 200-mesh screen under the water tap, the part that passes being allowed to run to waste, and the amount calculated by difference. In this case, as already stated, the portion remaining on 200 should after drying be re-screened on a 200 sieve as it will be found possible to make a further elimination of -200-mesh material in this way.

The assays of the various sizings will give a good indication of the degree to which comminution should be carried in order to liberate the precious metals, and expose them to the action of the cyanide. It is well to check the result by multiplying each assay by its proportional percentage, and dividing the sum of all the products by 100. The result should check closely the assay of the sample taken out before screen sizing.

The test may afterward be repeated using 0.1% cyanide strength, and only 2 or 3 days agitation, in order to get an idea as to the maximum size of particle that will give a good extraction under the usual conditions of slime treatment.

Having obtained an idea of the effect of cyanide treatment on each grade of material, an all-sliming test may be made, with the object of finding out the probable maximum extraction by simple cyanidation.

The ore is ground so that the whole will pass a No. 200 sieve, and 250 grams weighed up for a charge. Lime is added in accordance with the experience gained in the previous test, and the dilution made up to 3:1 with water to which the necessary amount of cyanide has been added to give a strength of, say, 0.3% KCN. The bottle is placed in the agitating wheel and treated for 3 or 4 days, the solutionbeing titrated each day for cyanide and alkali, and the strength maintained at the original figure.

It is impossible in the laboratory to imitate exactly the degree of grinding in a working scale mill by using a certain screen size as a standard. For instance, if it is decided that a 100-mesh product is desired an operator may produce several entirely different degrees of grinding though using the same mesh screen, according to the frequency of the screening. If screening is done after long intervals of grinding, on a bucking table or with closely set discs if using a disc grinder, the resulting product though nominally 100 mesh will have a far finer character as a whole than if the screening be frequent during bucking or if the discs of the grinder be set apart and gradually closed up after each screening. And probably none of the products obtained by these different procedures will correspond to the pulp of a mill where 100-mesh grinding is aimed at. In one case known to the writer the product obtained from a bucking table, putting everything through a 100-mesh sieve, only contained 50% of 200 material whereas the finished mill pulp on the same ore contained 5% of + 100- mesh material and 75% of 200. It is thus apparent that deductions drawn from laboratory extraction results on pulps all of which pass a given screen size must be received with discrimination.

In all experimental work a rule should be made never to dry prior to cyanidation a pulp that has once had water added to it. If, after amalgamating or concentrating a sample, it is desired to grind it finer, this should be done wet, with a pestle and mortar or some similar contrivance, and the screening should be done in water or solution.

The regrinding may be done satisfactorily in a small tube mill if certain precautions are observed. The usual tendency in this method is to overgrind the sample; that is, if it is desired to grind to 100 mesh and the sample is kept in the tube mill until all will pass the said screen the resulting product will be for practical purposes a 200 pulp. If a 200-mesh grinding is aimed at the resulting pulp will be far finer than would be produced on the milling scale with thesame end in view, and the result is thatthe extraction results may be quite misleading. To avoid this the product to be re-ground should be first wet screened on the desired sieve and the oversize only placed in the mill. This oversize is then allowed to grind for 5 to 15 minutes and is then removed and screened, the oversize being replaced in the mill. This process is repeated until all will pass the screen. A good scheme for regrinding wet sand is to take an ordinary bucking table and raise the back end a few inches with some woodenblocks and attach to the front a narrow wooden trough of hopper shape with a -inch nipple at the apex.

This may be clamped on or wedged onto the edge of the bucking table so as to be easily and quickly removed. The sample is then bucked down in the usual way using just enough water to form a paste that will not run off by gravity. Just as in dry bucking the pulp is periodically screened by washing it down with a wash bottle and a piece of rubber belting onto a screen of the desired size suspended over a bucket of water.

For purposes of weighing a given quantity for a test the specific gravity of the pulp may be determined or a portion of it dried to ascertain the percentage of moisture, and then sufficient of the wet pulp taken to give the required weight of dry ore, due allowance for contained moisture being made when adding water or solution to produce the dilution needed for treatment.

The reason for avoiding the drying of a sample is that this procedure, even when artificial heat is not applied, tends to oxidize its less stable constituents and produce changes which may materially affect the results of subsequent cyanidation.

Before starting a series of experiments considerable care should be expended in getting a really representative sample of the ore, mixing, grinding coarsely (say to No. 20 sieve), and cutting down to an amount sufficient to serve for the whole series. This should be again well mixed, and stowed away in a covered can or box.

gold processing | britannica

gold processing | britannica

For thousands of years the word gold has connoted something of beauty or value. These images are derived from two properties of gold, its colour and its chemical stability. The colour of gold is due to the electronic structure of the gold atom, which absorbs electromagnetic radiation with wavelengths less than 5600 angstroms but reflects wavelengths greater than 5600 angstromsthe wavelength of yellow light. Golds chemical stability is based on the relative instability of the compounds that it forms with oxygen and watera characteristic that allows gold to be refined from less noble metals by oxidizing the other metals and then separating them from the molten gold as a dross. However, gold is readily dissolved in a number of solvents, including oxidizing solutions of hydrochloric acid and dilute solutions of sodium cyanide. Gold readily dissolves in these solvents because of the formation of complex ions that are very stable.

Gold (Au) melts at a temperature of 1,064 C (1,947 F). Its relatively high density (19.3 grams per cubic centimetre) has made it amenable to recovery by placer mining and gravity concentration techniques. With a face-centred cubic crystal structure, it is characterized by a softness or malleability that lends itself to being shaped into intricate structures without sophisticated metalworking equipment. This in turn has led to its application, from earliest times, to the fabrication of jewelry and decorative items.

The history of gold extends back at least 6,000 years, the earliest identifiable, realistically dated finds having been made in Egypt and Mesopotamia c. 4000 bc. The earliest major find was located on the Bulgarian shores of the Black Sea near the present city of Varna. By 3000 bc gold rings were used as a method of payment. Until the time of Christ, Egypt remained the centre of gold production. Gold was, however, also found in India, Ireland, Gaul, and the Iberian Peninsula. With the exception of coinage, virtually all uses of the metal were decorativee.g., for weapons, goblets, jewelry, and statuary.

Egyptian wall reliefs from 2300 bc show gold in various stages of refining and mechanical working. During these ancient times, gold was mined from alluvial placersthat is, particles of elemental gold found in river sands. The gold was concentrated by washing away the lighter river sands with water, leaving behind the dense gold particles, which could then be further concentrated by melting. By 2000 bc the process of purifying gold-silver alloys with salt to remove the silver was developed. The mining of alluvial deposits and, later, lode or vein deposits required crushing prior to gold extraction, and this consumed immense amounts of manpower. By ad 100, up to 40,000 slaves were employed in gold mining in Spain. The advent of Christianity somewhat tempered the demand for gold until about the 10th century. The technique of amalgamation, alloying with mercury to improve the recovery of gold, was discovered at about this time.

The colonization of South and Central America that began during the 16th century resulted in the mining and refining of gold in the New World before its transferal to Europe; however, the American mines were a greater source of silver than gold. During the early to mid-18th century, large gold deposits were discovered in Brazil and on the eastern slopes of the Ural Mountains in Russia. Major alluvial deposits were found in Siberia in 1840, and gold was discovered in California in 1848. The largest gold find in history is in the Witwatersrand of South Africa. Discovered in 1886, it produced 25 percent of the worlds gold by 1899 and 40 percent by 1985. The discovery of the Witwatersrand deposit coincided with the discovery of the cyanidation process, which made it possible to recover gold values that had escaped both gravity concentration and amalgamation. With E.B. Millers process of refining impure gold with chlorine gas (patented in Britain in 1867) and Emil Wohlwills electrorefining process (introduced in Hamburg, Ger., in 1878), it became possible routinely to achieve higher purities than had been allowed by fire refining.

The major ores of gold contain gold in its native form and are both exogenetic (formed at the Earths surface) and endogenetic (formed within the Earth). The best-known of the exogenetic ores is alluvial gold. Alluvial gold refers to gold found in riverbeds, streambeds, and floodplains. It is invariably elemental gold and usually made up of very fine particles. Alluvial gold deposits are formed through the weathering actions of wind, rain, and temperature change on rocks containing gold. They were the type most commonly mined in antiquity. Exogenetic gold can also exist as oxidized ore bodies that have formed under a process called secondary enrichment, in which other metallic elements and sulfides are gradually leached away, leaving behind gold and insoluble oxide minerals as surface deposits.

Endogenetic gold ores include vein and lode deposits of elemental gold in quartzite or mixtures of quartzite and various iron sulfide minerals, particularly pyrite (FeS2) and pyrrhotite (Fe1-xS). When present in sulfide ore bodies, the gold, although still elemental in form, is so finely disseminated that concentration by methods such as those applied to alluvial gold is impossible.

Native gold is the most common mineral of gold, accounting for about 80 percent of the metal in the Earths crust. It occasionally is found as nuggets as large as 12 millimetres (0.5 inch) in diameter, and on rare occasions nuggets of native gold weighing up to 50 kilograms are foundthe largest having weighed 92 kilograms. Native gold invariably contains about 0.1 to 4 percent silver. Electrum is a gold-silver alloy containing 20 to 45 percent silver. It varies from pale yellow to silver white in colour and is usually associated with silver sulfide mineral deposits.

Gold also forms minerals with the element tellurium; the most common of these are calaverite (AuTe2) and sylvanite (AuAgTe4). Other minerals of gold are sufficiently rare as to have little economic significance.

Of the worlds known mineral reserves of gold ore, 50 percent is found in South Africa, and most of the rest is divided among Russia, Canada, Australia, Brazil, and the United States. The largest single gold ore body in the world is in the Witwatersrand of South Africa.

gold lost in ball mill - gravity separation & concentration methods - metallurgist & mineral processing engineer

gold lost in ball mill - gravity separation & concentration methods - metallurgist & mineral processing engineer

We sent a substantial amount ofquartz gold ore to a mill for processing. After a couple hundred tests on the material an average grade wascalculated. After milling for several days the mill says there is way less gold in the ore than what had been estimated.

Once milling began samples were taken once per shift, ball mill discharge, cyclone overflow, concentrate, and tails. Samples were sent to a lab for assay. With these samples the Lab has determined that there is at least 1 gpt missing that did not report to the concentrate or the tails. Theory from the lab is gold is stuck in the grinding circuit.

They are using flotation, metallurgy testing showed a decent recovery with gravity but a better recovery with flotation. Although in reality recovery was horrible below 60% This is mainly free gold, although it is very fine gold, as small as 10 micron size and the largest pieces being in the neighborhood of 500 micron. Also the ore has very little sulfides

If the cyclone underflow gold grade was higher than the cyclone overflow grade then you have free gold and you should look at putting a centrifugal concentrator in the grinding circuit. For low tonnage operations you can feed 100% of the ball mill discharge to the concentrator (this requires an extra pump, but is worth the effort). Modern units can recover free gold down to the 10 micron size range or finer.

In regards to the met balance, normal practice is to take the tails grade, feed tons, and gold produced and back calculate the head grade. Sampling the feed for head grade is always difficult. As a side comment, I'm not sure how your assay would be any more accurate than what is calculated in the met balance, but that is always the case to be argued between the miner and the mill guy. You can also compare the mill feed grade to the cyclone overflow grade to see if there are any losses in the grinding circuit.

You also need to check all the gold traps in the grinding circuit, i.e. cyclone feed pump box, cyclone underflow launders etc. They should be clean when you start your run, and cleaned out after you finish the run, including a full grind-out of the mill.

Free gold can also accumulate in the mill, either in the liners (at the Echo Bay Lupin operation when they took out the steel liners during a liner change they would put them in a secure area and grind off the surface to recover a lot of gold), or behind the liners (just ask any mill mechanic that does liner changes).

Thank you Andrew this is helpful, big problem with this material is the nugget affect when it comes to sampling. I was allowed to take 1 set of samples when I visited the mill, I took cyclone overflow and underflow, the difference was about 1.8 -1 and this is not a surprise as we know there is free gold.

This is a custom mill, I don't want to get to much into details as I don't want to smear anyone's name just yet. I'm just trying to understand whats happening and what can happen as for my one question to do with the head grade being way lower than expected grades.

Absolutely you can loose gold in the mill grinding circuit, in the classifier, in the bottom of the sand pump, behind the liners etc. particularly steel liners. When starting a new mill it will take some time before you can come up with a proper metallurgical balance, every crook and cranny, needs to to be filled before you can come up with what is in the head shows up in either the concentrate or the tailings. I have taken 40 ounces out of a small, 4' x 4' mill when I removed the liners, and any time you tear down a gold mill you have a pretty good pay day from trapped gold. Also since I am somewhat pessimistic, be sure there are no hidden traps, there on purpose, for the mill owner to make a little extra money, I have run into this, gold doe's funny things to people. My experience with custom mills is that you will likely never agree, best thing to do is come up with a good sampling system where you both can agree on a assay, sample for you, one for them, one for an umpire assay and then sell them the ore. Once you sell the ore to them you don't care what they do with it even if they want to make road gravel out of it.

Gold settling in tanks, gold room sumps or locked up in roasters This can be difficult to detect unless one goes looking for it or there is a policy of regular clean up. Similar problems occur in hydrometallurgical plants.

You may want to hire an experienced extractive metallurgist to give you a hand. This is the kind of thing I have done for over 50 years and helped many people with this kind of problems, it would likely be well worth the money.

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gold milling process -primitive and basic

gold milling process -primitive and basic

At the time, 1890, the Author said There is, of course, nothing for us to learn from this imperfect and rudimentary gold-extraction process described here, which is doubtless destined to disappear ere long, before the progress of scientific mining, now making itself slowly felt throughout the far East. I think it advisable, however, to put on record all such crude efforts, if only to enable us to trace more completely the evolution of our modern systems of mining, and to teach us by what widely-divergent methods different races of mankind have attempted to solve one, apparently simple, problem.

Their method of mining was then, and is now, the following: A small water-furrow is first brought in at the highest possible level on a suitable hill-side, and the stream is turned down the hill. By means of a heavy long wooden crowbar, shod with a long strongly- made chisel-pointed iron socket, and with the help of the stream of water, which rarely exceeds 50 cubic feet per minute, the surface- soil and weathered country-rock are loosened and sluiced away. No trouble is taken to save any of the gold washed down, except in one or two instances where rude riffles have been inserted in the tail-race; the race is, however, carefully searched for bits of quartz showing visible gold, which are picked out and put on one side. The surface of the shales is thus stripped, and any veins of gold that may be laid bare are then worked. The principal mining- tool is a rough kind of pick, and the use of explosives, or even of wedges, is quite unknown. Neither shovels nor barrows are used ; their places are taken by broad hoes and baskets, a pair of the latter, swung at each end of a stick and holding at least 70 pounds, being easily carried up steep grades by a Chinese miner. The tunnels, small and irregular, usually incline steeply upward ; they are rudely timbered, and as timber decays rapidly in this climate, these workings cannot penetrate far into the hills, but soon have to be abandoned, and the whole series of operations has to be recommenced.

A party of 27 miners, who owned and worked a rich hillside, considered themselves to be doing well when their entire days output (they do not work night-shifts as a rule) was a little over half a ton of quartz. The quartz, as extracted from the reef, is cobbed down with hammers to about pass a 1 J-inch ring, and is then carefully hand-picked, all stone showing visible gold, sulphurets or any other favorable indications being sent to the mill and the restbeing thrown away. From one-eighth to one-half is thus rejected. I have assayed many samples of this refuse rock, which carries from 3 to 10 pennyweights of free milling gold to the ton, so that it is quite worth milling according to our modern ideas.

At first the mode of crushing adopted by the Chinese consisted in heating the rock red-hot, quenching it in water and then pounding it down and rubbing it between two stomps. About 35 years ago atilt-hammer, made entirely without iron and having a stone head, was introduced, and is still much used by individual miners. About twelve years ago the battery of three to six hammers, worked by a water-wheel, was first employed. It is said to have been copied from mills for crushing the materials of joss-sticks. Tilt-hammer rice-mills are also built. Such water-mills are usually the property of a party of miners working together.

The foot-mill shown in Figs. 1 and 2 is of the usual type, from which there are but few unimportant departures. The entire falling weight is about 45 pounds, and the length of drop about 20 inches; as a rule, these mills are worked at 15 to 20 blows per minute.

The mill shown is built entirely without iron; the stone that forms the base of the mortar is a piece of hard quartzite or of barren reef-quartz, the same material being used for the hammer-head, which is firmly held in its socket by wooden wedges, the socket being kept from splitting by a stout hoop of rattan twisted round it. Some of the mills use iron hoops, and some have iron spindles for the hammer to work on; with these exceptions and one or two other very unimportant details, the construction is always the same, though the dimensions may vary a little. There is scarcely a house in the whole district that has not one of these mills.

The Chinese usually work these mills for about eight hours per day. A shovelful of quartz is first thrown into the mortar and the mill is then worked by the foot of the miner, who stands on one or other of the stones shown in the drawings, grasping the uprights or else a cross-bar that is sometimes fastened across them.

When the quartz is supposed to be crushed sufficiently fine, the hammer-head is propped up, and the crushed stone is scraped out and sifted through a circular sieve 15 inches to 20 inches in diameter, and about 1J inches deep. The sieve itself is made of thin strips of rattan about 0.1 inch in width. There are from 36 to 40 holes per square inch, so that the width of mesh varies between 0.04 and 0.06 inch. A man can crush in a working day, with one of these mills, from 70 lbs. to 140 lbs. of stone, according to its hardness.

The number of heads in a power-mill varies between 3 and 6, depending principally on the quantity of water available. As the district is well watered, the large majority are 6-stamp mills; out of 11 power-mills which it contains, 8 are 6-stamp mills. Figs. 3 and 4 show the usual type of the latter mills, from which pattern there is practically no departure. I could not even induce the Chinese to try a curved cam instead of a straight one, as they seemed to consider such innovations dangerous ; and they added that wood and water were both cheap enough. As will be noticed, the construction of the water-wheel is extremely crudethe water, which issometimes brought down very steep hills from considerable heights in small, highly-inclined ditches, strikes the flat buckets with considerable velocity, so that the wheel is partly an impact and partly a pressure wheel; the buckets are never more than half-filled at the best, and the wheel is sometimes allowed to wade in tail-water to the full depth of the shrouding. Much power is accordingly wasted, the amount of water consumed in driving one of these mills beingfrom 80 to 100 cubic feet per minute. The average number of drops of each head varies between 27 and 32 per minute; the length of the drop is about 2 feet, and the effective falling weight of the head is about 70 lbs. Thus only about one-third of the theoretical power of the water is utilized, but of course much of this loss of energy is due to the friction of the whole machine, notably between the straight cam and the tailpiece of the hammer. There are usually 3 men per shift working one of these mills, 2 being engaged in looking after and feeding the machine, while the third sifts thepounded stone as already described, throwing back under one of the hammer-heads whatever will not pass the sieve.

The cost of one of these mills complete, including a substantial shed over it thatched with palm leaves, but excluding the water- furrow, is said to be about very little, and they are supposed to last from 5 to 7 yearsneeding, however, constant repairs.

A stone hammer-head lasts from a week to a month, according to its quality. They are made, as in the foot-mills, from boulders of quartz rock, and it is mostly one mans business to search for these boulders in the bed of the stream, and, when found, to dress them into shape.

I tested the degree of fineness to which these mills reduce the quartz by differential siftings of a number of samples, taken by spoon-sampling the heaps of crushed ore lying at various mills. The results of some of my tests are given in the following table :

It appears from the above table that a great deal of the ore is crushed very fine (too fine, indeed), while some is not fine enough. As about 40 per cent, of the ore will pass through a 6,400 sieve, there must be much over-stamping, resulting, no doubt, in the production of a great deal of float-gold and slimes.

After the mill has been running for a longer or shorter period, according to circumstances, a clean-up takes place. The crushed ore is carried out in large wooden pails to a Chinaman, who washesit, squatting down by the side of a square pit, through which a small stream of clear water is kept running. The implement used for washing is a flat, somewhat conical wooden dish, cut from the spurs of certain hard-wood trees, and fashioned with much care. It is known as the dulang, and much resembles the Spanish-American batea, except that the section of the former is that of a very obtuse rounded cone, while the section of the latter is approximately that of a sphere.

A section of a typical dulang is shown in Fig. 5. Much importance is attached to the correct shape of the conical point, as it is in this that the precious metal is gathered together. The dulang is filled with from 10 to 15 lbs. of crushed stone, according to its size, and this is washed by a curious circular, combined with a slight undulatory motion, by which the particles of light, barren quartz are swept over the edge of the dulang, which is held just dipping below the surface of the water in the pit, while the heavier particles are collected in the rounded apex of the cone. When nearly cleaned, the gold and concentrates are transferred to a smaller, very carefully made and polished dulang, about 1 foot in diameter, in which thequartz is washed off as thoroughly as possible, and the gold, by a skillful jerk, is thrown clear from the sulphurets, and finally collected in a small brass dish. The sulphurets still retain much coarse gold, to which they cling obstinately. They are ground as fine as possible on a stone and re-washed several times, a good deal of the gold being thus separated and added to that previously obtained. Even then the sulphurets still carry much gold, the larger portion of which is free. They are stored away in jars while wet and allowed to rust, and after a time they are sometimes re-crushed and re-washed ; very often, however, they are merely allowed to accumulate and are not treated further. The first tailings are re-washed, and then stacked.

The cleaned gold is dried and melted over a small forge provided with a box-shaped wooden blower of the usual Chinese type. The fuel is charcoal. Tiny, conical crucibles, capable of holding about a couple of ounces of gold are used; the gold-dust is melted in these with borax and niter as fluxes; the slag is lifted off the surface of the gold when the latter is supposed to be clean, by means of an iron rod, and the gold is then granulated by pouring into water. If it is not considered to be sufficiently soft and pure it is re-melted, and the process is repeated until the gold is quite soft. The principal impurities removed seem to be sulphur, arsenic, a little copper, and perhaps traces of lead. Both the granulated gold and the crude gold-dust, as also gold got from river-washing, are used as currency in this district, coined money being scarcely ever seen here, and then only in the form of the old dollar.

In a partial wash-up at one of these mills, during my stay in the district, the following results, considered to be exceptionally good, were obtained, the quantity washed being as nearly as possible 2000 pounds of crushed ore:

As a general rule, there seems to be left in the tailings about one- third of the gold originally present in the ore, while there must be a considerable additional loss of float-gold carried away in the process of washing, due to the original fineness of some of the gold in the ore, and to the over-stamping already referred to.

From the average of these two assays it would appear that nearly one-third of the original proportion of gold is still left in the tailings. I might quote numerous other assays, but the results in all cases were approximately the same; there were no really clean tailings at all, in spite of the fact that they were all the result of handling sur- face-ores, where practically the whole of the gold was free. The losses above indicated appear enormous, but it must be remembered that the thrifty Chinamen throw nothing awaynot even tailings; however completely, in their opinion, these may be exhausted, they still pile them up and keep them. When, for any reason, their mill would otherwise be idle, they re-pound and re-wash their old tailings, and always get some gold out of them. The piles of tailings are, however, left exposed, so that a considerable proportion gets washed down into the streams and rivers by the heavy rains that occur at each change of monsoon ; and there are a good many Chinese of the poorer classes who make a sort of living by washing the sands in the river-beds, the gold they get being principally, to all appearance, that which has been thrown into the rivers by the miners up stream. It is noticeable that there is no gold, or very little, to be found in the rivers above the points where there are mines in operation. A fair days work of one Chinaman in the river-bed (say six hours actual work) was found, as the average of several trials, to produce an output of 7.3 grains of gold about .940 fine, worth say little in localcurrency. This quantity of gold was obtained by washing 22 large dulangs of gravel, each holding about 70 pounds of dirt.From the average of these two assays it would appear that nearly one-third of the original proportion of gold is still left in the tailings. I might quote numerous other assays, but the results in all cases were approximately the same; there were no really clean tailings at all, in spite of the fact that they were all the result of handling surface-ores, where practically the whole of the gold was free. The losses above indicated appear enormous, but it must be remembered that the thrifty Chinamen throw nothing awaynot even tailings; however completely, in their opinion, these may be exhausted, they still pile them up and keep them. When, for any reason, their mill would otherwise be idle, they re-pound and re-wash their old tailings, and always get some gold out of them. The piles of tailings are, however, left exposed, so that a considerable proportion gets washed down into the streams and rivers by the heavy rains that occur at each change of monsoon ; and there are a good many Chinese of the poorer classes who make a sort of living by washing the sands in the river-beds, the gold they get being principally, to all appearance, that which has been thrown into the rivers by the miners up stream. It is noticeable that there is no gold, or very little, to be found in the rivers above the points where there are mines in operation. A fair days work of one Chinaman in the river-bed (say six hours actual work) was found, as the average of several trials, to produce an output of 7.3 grains of gold about .940 fine.

It is interesting to note that in custom-milling, of which there is a good deal done here (many of the fossickers sending all the gold quartz they collect, whether by mining or picking out of the river- gravels, to one of the water-mills for crushing), the charge made is equal to just a few $U. S. per (long) ton of quartz, this payment including the washing of the gold, but not, so far as I can make out, its cleaning and melting.

It is obvious from the above description, that the total quantity of stone crushed by all the mills in the district, supposing them all to be going simultaneously, and including the foot-mills, could not exceed some 12 tons a day at the best, an amount that could be far more economically and efficiently handled in a five-stamp Californian mill of moderate power. Yet the total annual output of gold from this district (including, however, alluvial as well as reef-gold) is said to be 4861 ounces, fully .900 fine. The total number of men engaged in mining, in one way or another, is close upon one thousand.

buy ore ball mill for mineral processing | iron & gold ore ball mill

buy ore ball mill for mineral processing | iron & gold ore ball mill

Ore ball mill sometimes called ore grinding mill, is generally used in mineral processing concentrator, processing materials include iron ore, copper ore, gold ore, molybdenum ore and all kinds of nonferrous metal ore. The core function of the ore ball mill is to grind the materials, and also to separate and screen different mineral materials, and to separate the tailings, which is very important to improve the quality of the selected mineral materials.

The ore ball mill designed by our company, which is represented by gold ore ball mill and iron ore ball mill, is manufactured with high-quality materials and advanced technology. They have the characteristics of high efficiency, energy-saving, green environmental protection, simple operation, stable operation, and low failure rate, and have a good reputation in the industry.

The crushing ratio of the ore grinding mill is very large, and it is easy to adjust the fineness of the grinding product. The ore grinding mill has strong sealing performance and can be operated under negative pressure. It is widely used in chemical industry, metallurgy, new building materials and other fields.

We offer different types of ore ball mills for customers to choose from. There are energy-saving ore ball mill, dry and wet ball mill,wet grate ball mill, andwet overflow ball mill. Customers can choose to purchase according to material conditions.

Mineral processing is the most important link in the entire production process of mineral products. It is a process of separating useful minerals from useless minerals (usually called gangue) or harmful minerals in a mineral raw material by physical or chemical methods, or a process of separating multiple useful minerals The process is called mineral processing, also known as ore processing.

The first step in the ore processing is to select the useful minerals. In order to select useful minerals from ore, the ore must be crushed first. Sometimes, in order to meet the requirements of subsequent operations on the particle size of materials, it is necessary to add a certain ore grinding operation in the process.

The preparation before beneficiation is usually carried out in two stages: crushing screening operation and mineral classification operation. Crusher and ore ball mill are the main equipment in these two stages.

As a ball mills supplier with 22 years of experience in the grinding industry, we can provide customers with types of ball mill, vertical mill, rod mill and AG/SAG mill for grinding in a variety of industries and materials.

how i built a quick and easy home-made ball mill

how i built a quick and easy home-made ball mill

Anyone who has looked through my web site can see that I am fascinated with glass. I like to melt it, cast it, fuse it and turn it into new things. Eventually I got the idea of doing the ultimate glass hack and making my own glass from scratch. For that I needed a way of grinding and mixing the chemicals that would make up a batch of glass into a very fine and homogeneously mixed powder. I needed a ball mill. So naturally I decided to build my own. Here it is in all it's bodged together glory. It doesn't look like much, but it works great, and it cost almost nothing to build. As a bonus, this ball mill can also be used as a rock tumbler, or a glass tumbler to make your own "sea glass" at home. To use the mill as a rock tumbler, just leave out the steel balls, add rocks, tumbling grit and water, and let it spin.

Here is a video of my home-made ball mill in operation with a brief explanation of all the parts and how I put it together. For detailed descriptions of all the parts, how I built it, and how I use it, read further down this page.

The drum I used for the ball mill was originally a plastic container that held abrasive grit used in vibratory tumblers. It is about two liters in size. I had several empty containers of this type, and decided to put them to use in this project. They work pretty well in this application. There are a few potential problems. The container lids are not liquid-tight. So use as a rock tumbler would require adding a cork or rubber gasket. Also, a little bit of the plastic does get ground off the inside surface and contaminates the batch being ground. This is not a problem for my application because anything organic will be vaporized out of the mix long before it reaches melting temperature in my kiln. Contamination might be an issue for other uses. A steel drum would probably work better if you can find one, or make one, but it would be a lot louder in use.

Here you can see an overview of the ball mill with the drum removed. Construction is super simple. Just three pieces of wood plank banged together to make a platform for mounting all the parts. The platform is made from a 1X10 wooden plank 14 inches long. It sits on two pieces of 1X4 wood. Four inexpensive fixed caster wheels were mounted on top of the platform for the drum to roll on. They were mounted about 2 inches in from the edges of the platform, and 7.5 inches apart. The drive motor was mounted on the underside of the platform, and the dive belt comes up through a slot in the platform.

Here is a close-up showing how two of the caster wheels are mounted. The slot in the middle of the platform for the belt to pass through is also visible. The fixed caster wheels were quite inexpensive, and were one of the few items I actually had to buy to build this project.

Here is a close-up of the other side of the platform and the other two caster wheels. Also shown is a stop mounted on one side of the platform. It was found early on in using the mill that the drum tended to slowly walk toward one side and would eventually drop off the wheels. So I found a scrap piece of aluminum and mounted it the end the drum walked toward to act as a stop. The drum riding against the smooth aluminum surface doesn't seem to produce much friction.

The ball mill is powered by a fairly robust 12V DC motor salvaged from a junked printer. It had a pulley for a fine-toothed belt on it. It was left in place and it seems to drive the heavy round rubber belt well without slipping. The motor was mounted using screws on only one side, which were deliberately left loose. This allows the motor to pivot downward under its own weight to put tension on the belt.

A long, narrow slot was cut in the platform for the belt to pass through. I did it by marking out where I wanted it, drilling a hole at each end, and then cutting out the material between the holes with a jigsaw.

This photo shows the makeshift end stop that prevents the drum from walking off the casters. It is just a random piece of aluminum I found in my junk collection. It conveniently had some holes already drilled in it which made mounting easy. Just about anything that the drum will ride against nearly frictionlessly will work for a stop.

One of the few things I had to buy for this project, aside from the casters, was the steel balls. I found these online. They were quite inexpensive. I went with 5/8 inch diameter balls, which seem to work well in a mill this size.

I have been powering the ball mill with my bench variable power supply so I could fine tune the rotation speed. I wanted it to turn as fast as possible to speed grinding, but not so fast that centrifugal force pins the balls to the wall of the drum preventing them from tumbling over each other. With a little experimentation, the correct speed was found.

So far, this makeshift mill has worked well for me. It has been run for long periods with no problems. It does a good job of reducing even fairly chunky material into a very fine powder, and thoroughly mixing everything. The only real problem I have faced is accidentally over-filling the drum a few times. The drum should not be too full or the balls and material to be ground won't have enough free space to tumble around.

After a milling run, the contents of the drum are dumped out into a sieve over a bowl. With a few shakes of the sieve, the powder drops through the mesh into the bowl leaving the balls behind to be put back in the drum. The sieve also catches any bits that haven't been sufficiently ground down.

I need to add a disclaimer here for anyone thinking of using this sort of ball mill for milling gunpowder or other flammable or explosive powders. First of all, it is really not a good idea. You could cause a fire or explosion and destroy your place, or maybe even get yourself hurt or killed. So don't do it, and if you do it, don't blame me if something bad happens. I'll be saying I told you so. Also do not to use steel, ceramic or glass balls to grind flammable or explosive materials because they can create sparks as they bang against each other while they tumble.

Future improvements: The plastic container I am using is really thick-walled and sturdy, but using it in this application will eventually wear it out. I also get some plastic contamination in the materials I grind in it. So in the future I would like to replace the plastic container with a piece of large diameter steel or iron pipe with end caps. That should also help improve the grinding action as the steel balls bash against the hard walls of the pipe. If I switch to a steel or iron container, which would be heavier, I might also have to beef up the motor driving the unit. We'll see,

Other applications: As I mentioned at the top of the page, and in the attached video, this setup could also be used as a rock tumbler. The plastic container would be ideal for that. Another possible application for this unit is for grinding samples of gold ore, and maybe other metallic ores. One of my many hobbies is gold prospecting. It's often necessary to grind an ore sample to release all the fine particles of gold it contains so they can be separated. This unit may get used for that in the future too.

[Back to Mike's Homepage] [Email me] Other places to visit: [Mike's telescope workshop] [Mike's home-built jet engine page] [Mike's Home-Built Wind Turbine page] [Mike's Home-Built Solar Panel page] Copyright 2014-2018 Michael Davis, All rights reserved.

[Back to Mike's Homepage] [Email me] Other places to visit: [Mike's telescope workshop] [Mike's home-built jet engine page] [Mike's Home-Built Wind Turbine page] [Mike's Home-Built Solar Panel page] Copyright 2014-2018 Michael Davis, All rights reserved.

[Mike's telescope workshop] [Mike's home-built jet engine page] [Mike's Home-Built Wind Turbine page] [Mike's Home-Built Solar Panel page] Copyright 2014-2018 Michael Davis, All rights reserved.

ball mill for sale | grinding machine - jxsc mining

ball mill for sale | grinding machine - jxsc mining

Ball mill is the key equipment for grinding materials. those grinding mills are widely used in the mining process, and it has a wide range of usage in grinding mineral or material into fine powder, such as gold, ironzinc ore, copper, etc.

JXSC Mining produce reliable effective ball mill for long life and minimum maintenance, incorporate many of the qualities which have made us being professional in the mineral processing industry since 1985. Various types of ball mill designs are available to suit different applications. These could include but not be restricted to coal mining grate discharge, dry type grinding, wet mineral grinding, high-temperature milling operations, stone & pebble milling.

A ball mill grinds ores to an end product size of thirty-five mesh or finer. The feeding material to a ball mill is treated by: Single or multistage crushing and screening Crushing, screening, and/or rod milling Primary crushing and autogenous/semi-autogenous grinding.

Normal feed sizes: eighty percent of six millimeters or finer for hard rocker eighty percent of twenty-five millimeters or finer for fragile rocks (Larger feed sizes can be tolerated depending on the requirements).

The ratio of machine length to the cylinder diameter of cylindrical type ball mills range from one to three through three to one. When the length to diameter ratio is two to one or even bigger, we should better choose the mill of a Tube Mill.

Grinding circuit design Grinding circuit design is available, we experienced engineers expect the chance to help you with ore material grinding mill plant of grinding circuit design, installation, operation, and optimization. The automatic operation has the advantage of saving energy consumption, grinding media, and reducing body liner wear while increasing grinding capacity. In addition, by using a software system to control the ore grinding process meet the requirements of different ore milling task.

The ball mill is a typical material grinder machine which widely used in the mineral processing plant, ball mill performs well in different material conditions either wet type grinding or dry type, and to grind the ores to a fine size.

Main ball mill components: cylinder, motor drive, grinding medium, shaft. The cylinder cavity is partial filling with the material to be ground and the metal grinding balls. When the large cylinder rotating and creating centrifugal force, the inner metal grinding mediums will be lifted to the predetermined height and then fall, the rock material will be ground under the gravity force and squeeze force of moving mediums. Feed material to be ground enters the cylinder through a hopper feeder on one end and after being crushed by the grinding medium is discharged at the other end.

Mining Equipment Manufacturers, Our Main Products: Gold Trommel, Gold Wash Plant, Dense Media Separation System, CIP, CIL, Ball Mill, Trommel Scrubber, Shaker Table, Jig Concentrator, Spiral Separator, Slurry Pump, Trommel Screen.

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