You probably already know that the size and type of stone you need for your project depends on how you intend to use the stone. #57 stone is a crushed stone aggregate used in a variety of construction and landscaping projects. In short, #57 stone is a gravel-like material consisting of specifically sized stones. You may not know that gravel and crushed stone are different materials. Gravel is usually less angular because it naturally occurs by erosion. Crushed stone comes from natural rock deposits and is angular and jagged in shape.
Crushed stone is made from a suitable rock formation during the mining process. A crusher breaks down the rock into various sizes. Crushed stone varies in size. The number 57 is a number that refers to the size sieve that was used to screen and sort the stone. It means that the stone was put through the #57 sieve which produces gravel stones of about 1 to 1.5 in size. #1 crushed stone refers to the largest sized crushed stone. It is about 2 to 4 in size. Its uses are for tor larger jobs such as culvert ballast. At the other end of the size chart is a very small-sized stone #411 stone. It consists of a mixture of stone dust and #57 stone. It is used when the project calls for stone dust that mixes with the larger stone and settles well.
When you order #57 stone, you are ordering a gravel-like material with individual stones about the same size as nickels and quarters. The stone material itself may consist of granite, limestone, washed gravel, argillite or quartzite. You can also find #57 crushed concrete. If you are looking for a specific type of stone, you will want to specify your preference as to the type of rock you want when you order it.
#57 stone is one of the most commonly used types of crushed stone due to its versatility. It is ideal for a variety of projects. It is used as aggregate in concrete. It works well as a base for building sidewalks, asphalt roads, driveways, and railroad ballast. In asphalt paving, the tar and other aggregates are able to sink into the spaces between the stones, creating a firm, solid base for it.
If you want to leave a road or driveway unpaved, #57 stone is very suitable for that purpose. The angular, irregular shape of this stone allows it to mesh together on a flat surface and hold its shape well, providing a relatively stable unpaved surface.
Another way this stone is frequently used is to provide drainage. Water percolates through the stones and channels water away from wet areas. It is the first choice for use in French drains, septic drainage fields and other types of drainage projects. You will also note that it is the preferred gravel for managing drainage around retaining walls, lining underground pipes, sewers and utility lines/cables.
The most important consideration is the size and type of stone you need for the project. The stone size is what determines the best application for it. Your project may call for a couple of different types and sizes of stone, but #57 stone provides three important benefits.
#57 stone may not be the appropriate stone for use on the side of a hill or a sloped surface. The weight and shape of the stone make it prone to sliding and washing in heavy storms. Talk to your dirt supplier about the best kind of material to use on a sloped surface.
#57 stone is the ideal size and weight for correcting and controlling drainage just about anywhere on your property. It allows water to drain naturally and prevent flooding and pooling. With all of those benefits, why would anyone use anything other than #57 stone? As noted earlier, the size and shape of the stone determine its most appropriate use. Like any other stone, #57 crushed stone is not suitable for use in every project. Here are some factors you need to consider before you order stone for your project.
#57 stone works for improved drainage, but it will be overwhelmed if simply placed on top of a dirt or mud surface. If you want to use the stone to improve drainage, you will need to do some site prep involving excavation to make the project successful. Your dirt supplier or landscape architect can advise you on what to do and whether you need to consider different stone or stone in addition to #57.
By itself, #57 stone will not create a highly compacted surface. You will need to use other materials or add material to the stone to achieve a firm surface. Your dirt supplier or project engineer can advise you on the material you need to use to achieve your desired result.
Before you begin your project, speak with the experienced contractors at Dirt Connections. They will help you determine the right kind and size of stone you need. They can also help you calculate the quantity to ensure you will receive the proper amount needed to complete your project.
I have madea number of general remarks regarding the character of product delivered by crushers of various types, and under different conditions of operation. Generalities are of value only if we have some standard to which comparisons may be referred; therefore, we should like to present more specific information on the kind of product to be expected from crushing equipment under average operating conditions. Much of the data on which sizing/designcurves and tables are based comes from operations involving those two very important types: gyratory and jaw crushers; therefore these curves and tables are more nearly representative of the work of these types than of rolls or hammermills. They may be used for these latter types however if due allowance is made for peculiarities of each type, as pointed out in the descriptions of the different machines.
The preparation of a set of product gradation curves involves a considerable amount of work in the collection of the necessary test data, and a certain degree of discrimination in sorting such data and weeding out erroneous results. There are several reasons why no set of product gradation curves can be regarded as more than reasonably close approximations. First among these is the variation in physical structure of the many materials for which crushers are used; rocks exhibit a high degree of rugged individualism in their reaction to crushing. This variation is frequently quite pronounced between different ledges in the same quarry.
Gradation of the crusher feed also has its effect upon the product analysis. This is true even of screened feed, although deviations from the average are not likely to be so wide as they are for unscreened material, such as quarry-run or mine-run rock. We have commented on other variable factors, such as choke versus regulated feed, straight versus curved concaves, and so forth.
Fortunately, most materials do follow a certain definite gradation pattern and, by averaging a large number of test results, it is possible to plot a group of curves which can be classed as fairly close approximations. Even though approximate, these curves are of great value in crushing-plant design, or in the solution of problems concerning additions or alterations in the plant flowsheet. They simplify the problem of selecting secondary and tertiary crushers, as well as elevating and conveying equipment, and they are invaluable in the calculation of screen sizes. In short, they eliminate much of the old-time guess work in the preparation of the plant flowsheet.
Gyratory and jaw crushers are always rated at certain open-side or close-side discharge settings. In order that we may select the particular curve, of a group of curves, which will most nearly represent the product of a crusher having any given discharge setting, it is important to know approximately what percentage of the total output will pass a screen opening of equal dimension. It was universal practice in past years to designate such screen openings as ring-size for the very logical reason that the leading screen of that day, the revolving type, was, almost without exception, fitted with sections having round holes. Now that the vibrating screen, with its wire cloth or square-punched steel plate sections, has pre-empted the field there is no longer any excuse for adhering to the ring-size product designation.Above is alist of the approximate percentages of product passing a square opening test sieve whose holes are equal to the discharge setting of the crusher. Several different conditions are tabulated, and each condition is accompanied by estimates for four different classes of material.
In gravel pit operations it will usually be found that some one of these listed base rocks will predominate, and no great error will be introduced if this predominant rock is used as the basis for product calculations. Most base rocks will be close enough in physical structure to one of the listed varieties so that the percentages can be used for them without serious error. The same statement applies to the product gradation curves to be discussed. It must be remembered that the entire process of securing and compiling data of this nature is, at best, one which is susceptible of only approximate results.
It was formerly the custom to consider one set of product gradation, or screen analysis, curves as being suitable to represent the products of both primary (unscreened) and secondary (screened) feeds, making no allowance for the undersize material which is always present, to some extent, in quarry-run and mine-run materials. The average quarry does not produce as much of this undersize rock as the average mine, but the usual practice in mining operations is to scalp off most of the undersize ahead of the primary crusher, whereas this practice is the exception rather than the rule in quarry operations. As a matter of fact, where the secondary crushers are fitted with straight concaves, or jaw plates, as used to be standard practice, the dif-ference between product curves on screened and unscreened feed was not significant, and no great discrepancy was introduced by considering them under the one heading.
With the introduction of non-choking concaves in the standard gyratory crushers and reduction crushers, and the development of high speed fine-reduction crushers with high choke points, it soon became apparent that there was a substantial difference in the screen analyses of the two kinds of product, that is, crusher products on unscreened and screened feeds. The difference is especially significant in the lower part of the curve, where undersize in the feed would naturally show up, and where the cleaner breaking of the non-choke crushing chamber would likewise be reflected.
Here above isshown a family of curves for primary crushing of unscreened feed, such as the average quarry-run material in which the undersize (minus crusher setting) rock is present in proportions normally resulting from blasting operations. The same curves may be used for mining operations with stationary bar grizzlies ahead of the primary crusher.
In such operations the amount of undersize going into the crusher will usually be about the same as for the quarry operation without pre-scalping. It should be noted that the test data on which these curves are based were taken from gyratory and jaw crusher operations, but, as we have stated before, they may be used for other types of crushers if allowance is made for the characteristics peculiar to each type. As a matter of fact, so far as crushers of the Fairmount single-roll type are concerned, there is a natural compensation which brings the curves fairly well into line. The Fairmount crusher is inherently a somewhat cleaner breaking machine than either the standard gyratory or standard jaw types, but the class of rock for which the former crusher is largely used is usually subject to greater than average degradation during the blasting and loading operations in the quarry, which tends to level out the difference in crushing performance.Using Crusher and Screen Charts
The method of using the curves is so simple as to require little comment. The vertical axes represent material sizes, which may be taken as either square or round openings; provided of course that the same shape of opening is used throughout any particular analysis. The horizontal axes represent cmmdative percentages passing corresponding screen openings. If we wish to check the product to be expected from a crusher set at some predetermined discharge opening, we first refer to the table showing the approximate percentage of product which will pass an opening equivalent to the crusher setting. This gives us a point in the group of curves which may, or may not, be exactly on one of them. In the latter case we interpolate by following an imaginary curve between the two curves on either side of our point. We can thus tabulate cumulative percentages passing all of the product sizes in which we may be interested. Non-cumulative percentages; which are important because they are used to determine expected amounts of specific products are simply the difference between the upper and lower cumulative percentages for the particular product limits under consideration.
For those not familiar with the use of product gradation curves an example may be helpful. Suppose that a tentative selection of a 3.5 open- side discharge setting has been made for a standard gyratory primary crusher to be used for crushing quarry-run limestone. Referring to the table which lists percentages of product passing an equivalent square opening, we find that 85 to 90% of the crusher product should pass a 3.5 square opening. Choosing the lower percentage, to be on the conservative side,, we follow the horizontal line, denoting the 3.5 product size in the curve chart, over to the vertical line marking the 85% value. We find that the point we have established does not fall directly upon any of the group of curves, but lies so close to one of them that it may be used without appreciable error into our calculations.
Let us suppose that we wish to know how much of the product of our primary crusher will be retained on a 1.5 square opening screen, so that we may estimate the size and number of secondary crushers required to recrush the plus 1.5 contingent. Following the curve down to the 1.5 line, we find that 43% of the primary crusher output may be expected to pass this screen opening; 57% will be retained, which means that we must provide secondary crushing capacity to take care of 57 tons for each 100 tons fed to the primary crusher.
Occasionally it happens that we wish to scalp off a salable product from the output of the primary crusher; for example, a plus 1.5 minus 3.5 material for highway base- rock. The difference between the cumulative percentages at the 3.5 and 1.5 points on the curve gives us the amount, of such product to be expected from the output of the primary crusher This is 85 minus 43, or 42% of the primary crusher product.
If our problem had covered a crushing condition calling for 80 instead of 85%passing the opening equivalent to the crusher setting, we would have found that our point fell exactly on a curve, regardless of what crusher setting we had selected. This is because all of the family of curves are based on the 80% line. Obviously a group of curves might be based on any percentage line, but it is usual practice to choose the 80 or 85% values.
It will be noted that the curves bend upward in very marked fashion above the 75-85% region. This simply reflects the tendency of practically all materials to slab, or spall, to some extent in the crusher. As a matter of fact, product gradation in this upper range (above the open- side setting of the crusher) is of a distinctly uncertain and variable nature, and about all that a group of curves can do is to reflect the general tendency. Fortunately the exact screen analysis in this fraction of the primary crusher output is recrushed in succeeding stages, and all that is required is to know approximately how much of it there will be to recrush.
Although the group of curves we have been considering are intended for calulations involving primary crushing operations, they may also be used for secondary crusher products in those cases where no screening is performed between primary and secondary stages. Such an arrangement is seldom encountered in modern plant design, except where large jaw crushers, set very wide, are followed by a secondary, usually of the standard gyratory type, to reduce further the very coarse output of the jaw crusher to a size which can be handled by the recrushing, screening, and elevating equipment in the balance of the plant. In such cases it is simplest to consider the two-stage set-up as a single machine with discharge opening equal to that of the secondary crusher.
The group of curves on the rightischarted from screen analyses of the products of crushers receiving screened feed. They are useful in predicting the character of output from secondary and tertiary crushers, and are of great value in the preparation of plant flowsheets, and in calculating vibrating screen capacities. Their use in the latter connection will be discussed in the screening section of this series.
There is no need for extended comment on this group of curves; the method of taking off cumulative percentages, and non-cumulative fractions, is exactly the same as for the chart we previously discussed. The difference in the shape of these curves is attributable to the absence of fines in the crusher feed, and to the cleaner breaking action of the modem reduction crusher.
The product gradation curves for screened feed, described under the preceding sub-heading, can be used as a basis for calculating approximate screen analysis of products from closed-circuit crushing stages, but the values cannot be taken directly from the curves.
For example, consider a crusher set to turn out a product 70% of which will pass a 5/8 square opening, and in closed circuit with a screen which is equipped to remove the minus 3/4 product. Thecurve shows that approximately 85% of the crusher product will pass the 3/4 square openings.
Suppose that we wish to know how much minus 0.25 fines we may expect from the circuit.We do not go to the curve which touches the 100 percent ordinate at the 3/4 value; we calculate the percentage from the same curve which was used to predict the proportion of minus 0.75 in the crusher discharge. This curve shows approximately 29 percent of minus 3/4 in the material as it comes from the crusher, or 29 tons of fines in each 100 tons of crusher output. But, for the circulating load, we are only interested in that fraction of the crusher output which will pass the 3/4 screen, which is 85 tons.That part of the product gradation curve which lies below the 85 percent valuerepresents the gradation of the finished product, and 29 tons out of each 85 would be minus 0.25.
Let x equal percentage of minus 0.25 in the finished product, then x:100=29:85 or x = 34.1 percent of minus 0.25 rock from the closed circuit operation. Any other size of product may be estimated in a similar manner. Note that if we had used a curve touching the 100 percent ordinate at the 0.75 value, we would have arrived at a value approximately 50 percent for the minus 0.25 fraction; a value which is obviously erroneous for rock of average characteristics. We will comment on closed circuit crushing, and upon certain assumptions which have to be made in closed circuit calculations, in a later discussion of reduction-crushing.
Although the long established practice of designating crusher products by ring-size is not compatible with present-day screening practice, there are occasions when it is desirable to convert our calculations from one shape of opening to the other. So far as the curves themselves are concerned, once we have established the shape of screen openinground or squarewe can use them for either so long as we stick to one shape throughout the process of taking off percentages-passing. If, as occasionally happens, we have to deal with both shapes of screen opening in the same set of calculations, one or the other of them must be converted to equivalent sizes of the opposing shape. For example, if most of the screen openings are to be square, but one or two of them must be round, the round-hole sizes should be expressed in terms of equivalent square openings.
Inasmuch as the table of crusher settings versus equivalent product percentages is based on square openings, it is necessary to convert to equivalent round openings before this table can be used for such openings.
Below is the information needed to make conversions from round to square holes, or vice versa. The two columns at the left showing equivalent sizes for flat testing screens, are the columns to use in connection with crusher product calculations.Admittedly, listings of equivalent round and square holes, such as we show in this table, can be only approximately correct for the many different materials with which we must deal in crushing and screening computations. The infinite variety of shapes encountered renders absolute accuracy an impossible attainment. Practical experience, however, indicates that the comparisons shown in our table are in most cases close enough for all practical purposes.
Product SizeCorresponding Size Holes Through a flat testing screen Allis-Chalmers vibrating screenRevolving Screen Round holes Square holesRound holes Square holesRound holes 1/83/325/321/85/32 3/83/327/323/161/4 1/43/149/321/41/16 1/21/411/321/123/8 3/83/107/163/81/2 1/43/81/23/163/18 1/21/101/41/25/8 3/21/25/81/1811/10 3/82/1011/106/83/4 11/105/83/411/107/8 3/411/107/83/41 7/83/415/187/81 1/8 17/81 1/1612/101 1/4 1 3/811 2/181 1/181 3/8 1 1/41 1/161 3/81 1/71 2/14 1 3/81 1/81 1/161 1/41 3/4 1 1/21 1/41 3/181 3/81 7/8 1 5/81 3/81 3/41 3/102 1 3/41 1/21 7/81 3/162 1/4 1 7/81 5/821 3/42 3/8 21 3/42 1/81 7/82 1/2 2 1/81 7/82 1/422 5/8 2 1/41 15/182 3/82 1/162 3/4 2 3/822 1/22 1/82 11/16 2 1/22 1/82 6/82 1/43 1/8 2 5/82 1/42 3/42 3/83 5/12 2 3/42 3/82 7/82 1/23 1/2 2 7/82 1/232 5/83 5/8 32 5/83 1/42 3/43 3/4 3 1/42 3/43 1/234 3 1/233 3/43 1/44 3/8 3 3/43 1/443 1/24 3/4 43 1/24 1/43 3/45 4 1/23 7/84 3/44 1/85 1/2 54 1/45 1/44 1/26 1/4 5 1/24 3/45 3/456 7/8 65 1/46 1/25 1/27 1/2 6 1/25 1/275 3/48 767 1/26 1/28 3/4 7 1/26 1/2879 3/8 878 3/47 1/210 8 1/27 1/49 1/47 3/410 1/2 97 3/49 1/28 1/411 1/4 9 1/28108 1/211 3/4 108 1/210 1/2912 1/2
#57 Rock Crushed Concrete is a crushed concrete aggregate.Sizes of #57 Stone range from 1 inch to 1/2 inch.Common applications:Driveway GravelRV PadsDrainage ControlFrench DrainsWalkwaysConcrete MixRecycled materials can contain metal and other debris.
The Jwaneng diamond pipe has a current depth of 300m, which is expected to reach 675m. It was discovered in 1972 and reached full production in July 1982. The mine was officially inaugurated in August 1982.
Jwaneng is the eighth biggest diamond mine in the world with an estimated reserves of 88.3Mct (70.1Mt grading 1.26ct/t diamond) as of December 2012. The mine has an average production rate of 12 to 15 million carats per year.
The kimberlite deposits at Jwaneng are mined as a series of cut-downs into the earth. P&H 250XP blast-hole machines are used for the drilling. Approximately 58.72 million tonnes of ore was moved to the surface in 2010.
In-pit crushing method is applied at the mine. The recrushing plant processes the primary crushed ore and prepares it for diamond recovery. The dense-medium cyclones separate the waste from the diamonds after the secondary crushing.
The mining fleet includes the advanced Komatsu 930 haul trucks and Bateman semi-mobile crushers. Gemcom integrated mine production and management system is used for the ore transportation. The ore is carried to the processing plant using 250t payload capacity dump trucks.
The Aquarium processing plant comprises of Completely Automated Recovery Plant (CARP) and Fully Integrated Sort House (FISH). The Aquarium facility applies laser and x-ray sorting technology for diamond recovery.
The construction of $3bn Cut-8 expansion project began in 2010. It is expected to extend the mine life to 2028 and provide access to 95 million carats of diamonds. Jwaneng will feature among the top super-pit mines in the world upon completion of the Cut-8. The infrastructure and plant upgrades for the expansion project were completed in September 2012.
The construction of modular tailings treatment plant commenced in 2013. It will have a capacity to treat 2.5Mtpa and is expected to produce 18 million carats in 20 years. The plant is expected to be fully operational in 2014.
The engineering, procurement and construction management (EPCM) services contract for installing the mine surface infrastructure was awarded to Fluor. The contractual scope also included the earthworks, civil construction, pilings, structural steel erection and electrical installation.
Majwe, a joint venture of Leighton Africa, Basil Read Mining and Bothakga Burrow, was awarded the contract for providing mining services for the Cut 8 Phase 2. The contract services included mine scheduling, drilling and blasting, waste removal and limited ore mining.
Plant will be completely wired with S.O. cord from the motors back to an electrical control panel. Panel includes four (4) spare starters for auxiliary conveyors (wiring for these conveyors is not included). System will be tested prior to shipping to jobsite.