a complete ore beneficiation production line consists of a vibrating feeder, a crusher, a vibrating screen, a ball mill, a dryer, a concentrator, a magnetic separator or flotation machine and a spiral classifier.
The preparation usually consists of two stages: crushing and mineral grading. In order to separate useful minerals from ore, the ore should firstly be crushed. Sometimes in order to meet the requirements of the material size of the subsequent work, it is necessary to add a certain crushing operation.
The ore will be sorted after being crushed and the useful minerals and gangue are selected, or the various useful minerals are separated from each other, which is the main part of the beneficiation. The ore dressing methods include magnetic separation, gravity separation, froth flotation, electrification, and chemical separation.
Magnetic separation is perfomed in an inhomogeneous magnetic field using the difference in magnetic properties of the mineral particles. Those minerals with strong magnetism are selected by the magnetic separator with weak magnetic field, such as magnetite and pyrrhotite; whereas those with weak magnetism are sorted by that with strong magnetic field, such as hematite, siderite, ilmenite and wolframite.
The froth flotation is an essential concentration process. In this process, several kinds of particles are separated by the surface chemistry of the particles. Additionally, it can handle materials whose size is less than 0.2 to 0.3 mm and it can also be used to select intermediate products in metallurgy as well as ions, treat wastewater. As is manifested in statistics, more than 90% of non-ferrous metal is separated in a flotation separation process.
Gravity separation refers to the sorting operation based on the specific gravity of the mineral raw material particles. Gravity separation is the main processing method for selecting black tungsten ore, cassiterite, gold, coarse iron and manganese ore; and it is also widely used for rare metal ore. This method tends to cut much cost and cause little environmental pollution.
Since most of mineral processing products are wet, it is necessary to remove the moisture from the mineral processing products before smelting. Dewatering operations are often carried out by means of concentration, filtration and drying.
Concentration is the action of gravity or centrifugal force to precipitate solid particles in the beneficiation product to remove part of the water, which is usually carried out in a concentrator.
Drying, the final stage of dehydration, refers to the reducing of moisture according to the principle of heating and evaporation. However, it is only used when the dehydrated concentrate needs to be dried. This operation is generally carried out in a dryer.
The materials are firstly sent into the crusher for primary crushing through the vibrating feeder, and then into the ball mill for further grinding. After that, the crushed materials are into the spiral classifier for washing and grading. The flotation cell or the magnetic separator will further process them for ore separation. The concentrator and rotary dryer are finally used for drying and dewatering and the materials that come out of the concentrator are the valuable minerals. Additionally, the two mentioned machines are optional and you can make a decision relied on your actual needs.
The raw ore of this project contained 3.68% of lead, 2.85% of lead in lead oxide, and 77.45% of lead oxidation; 16.06% of zinc, 15.93% of zinc in zinc oxide, and 99.20% of zinc oxidation. It can be seen that the raw ore was a refractory polymetallic ore. The main metal minerals were galena, white lead, sphalerite, hemimorphite, siderite, pyrite, limonite, hematite, and silverite. The main non-metallic minerals were quartz, feldspar, hornblende, chlorite, calcite, mica and some clay minerals.
Crushing and screening stage: two stage and one closed circuit crushing and screening process was adopted. The raw ore was transported to the raw ore bin of the dressing plant by truck. A fixed grid screen was set on the top of the bin. The large pieces of ore on the screen were crushed manually. The qualified ores under the screen were sent to the jaw crusher for coarse crushing by the electric vibrating feeder. The coarse crushing products were sent to the double-layer circular vibrating screen by No.1 belt conveyor for screening. The upper screen opening of the circular vibrating screen was 20 mm and the lower screen hole was 10 mm. The products on the screen would flow to No.2 belt conveyor for fine crushing, and the fine crushing products would be sent to No.1 belt conveyor to round vibrating screen for screening again. The fine materials under the screen were washed by washing water to the classifier for a stage of ore washing operation, and the overflow was pumped to the ore washing overflow buffer tank beside the powder ore bin by Xinhai wear-resistant rubber pump, and the ore washing return sand and the intermediate products of the vibrating screen were transported to the powder ore bin by No.3 large angle belt conveyor.
Grinding and beneficiation stage: two stage and one closed circuit grinding + lead flotation (two roughing, one scavenging and four cleaning) + zinc flotation (two roughing, two scavenging and four cleaning) process flow was adopted. A tilting feeder was set at the bottom of the round powder ore bin. The fine ore was sent to a wet grid type ball mill through No.4 belt conveyor for grinding, and the ball mill was equipped with Xinhai wear-resistant cyclone for classification. The return sand of hydrocyclone returned to the ball mill, while the overflow was sent to the secondary cyclone group for classification. The grit of the cyclone group was returned to the secondary overflow ball mill for grinding, and the overflow entered the high-efficiency stirring tank before flotation. The feeding of two-stage classification hydrocyclone was completed by Xinhai wear-resistant rubber pump.The pulp entered the lead flotation system after being fully medicated. Two roughing, one scavenging and four cleaning processes were adopted for lead flotation. SF-4 flotation machine was used for I and II scavenging, SF-2 flotation machine used for cleaning I and II, and SF-2 flotation machine used for III and IV cleaning.The lead concentrate was pumped from a slurry pump to a high-efficiency thickener. The lead tailings were pumped from a vertical slurry pump to a ceramic filter for stage dewatering. The filtrate was pumped by a clean water pump to a 10m lead flotation supply tank, and the filter cake entered the high-efficiency stirring tank for slurry mixing and chemical treatment, then entered the next high-efficiency stirring tank for further chemical treatment, and then entered the zinc flotation system.Two roughing, two scavenging and four cleaning processes were adopted for zinc flotation. SF-4 flotation machine was used for roughing I, II and scavenging I and scavenging II. SF-2.8 flotation machine was selected for cleaning I, cleaning II and III and cleaning IV.Zinc concentrate was pumped from Xinhai wear-resistant rubber pump to high-efficiency thickener, and zinc tailings were pumped from Xinhai wear-resistant rubber pump to high-efficiency transformed thickener.
Concentrate dehydration stage: lead and zinc concentrate were dehydrated by means of mechanical dehydration. After being thickened by high-efficiency transformed thickener, the lead concentrate flowed into the disc filter for filtration, which was then transported to the lead concentrate storage yard by a NO.5 belt conveyor, and the filtrate was pumped to the high-efficiency transformed thickener. After the zinc concentrate thickening through the high-efficiency transformed thickener, the gravity flow entered the disc filter for filtration, and the filter was transported to the zinc concentrate storage yard by a No.5 belt conveyor, and the filtrate was driven to the high-efficiency transformed thickener.
Tailings dehydration stage: mechanical dehydration was adopted. After the tailings were thickened by the high-efficiency reformed thickener, the self-flow entered the disc filter for filtration, which was then transported to the tailings yard by two NO.5 belt conveyors. The filtrate was pumped from 40PV-SP to the high-efficiency reformed thickener. The overflow of the thickener was all collected into the overflow water settling tank, and after settling and clarifying, which was pumped by the clean water pump to the zinc flotation supply tank.
Process: Two-and half-stage closed-circuit crushing - one-stage closed-circuit grinding - flotation process of one-stage roughing, two-stage scavenging and two-stage concentration - two-stage mechanical dewatering
Process: Two stage and one closed circuit crushing and screening - two stage closed circuit grinding - lead flotation (two roughing, one sweeping and four refining) - zinc flotation (two roughing, two sweeping and four refining) - dewatering process of lead and zinc concentrate.
Process: Two and half circuits & one closed circuit crushing and screening- two-stage closed circuit grinding & classification-thickening- alkali pretreatment-two stage cyanide leaching- three stage washing-zinc powder change- tailings dry stacking.
Most of the iron minerals in a single magnetite are magnetite. Because the single magnetite is simple in composition, strong in magnetism, and easy to grind and sort, the weak magnetic separation method is often used for selection.
When the particle size of grinding is greater than 0.2mm, most iron ore magnetic separation plants often adopt a process of grinding and magnetic separation; When the grinding particle size is less than 0.2mm, the two-stage grinding-magnetic separation process is used; If qualified tailings are separated in the rough grinding stage, the magnetite magnetic separation plant should adopt the stage grinding-magnetic separation process; For dry and water-scarce areas, the magnetite ore dressing plant may consider using dry grinding-dry magnetic separation process; For the depleted magnetite-rich ore or magnetite-rich ore, the gangue can generally be removed by dry magnetic separation process, and then the lump-rich ore is obtained, and then the concentrate is obtained through the grinding-magnetic separation process.In order to obtain high-grade concentrate, magnetite concentrate can be treated by reverse flotation or high-frequency fine screen. In addition, in order to further improve the recovery rate, processes such as tailings gravity separation may also be considered to further recover magnetic minerals.
The gangue containing polymetallic magnetite often contains silicate or carbonate minerals, associated with cobalt pyrite, chalcopyrite and apatite, etc. Generally, the combined process of weak magnetic separation-flotation is used, that is, weak magnetic separation process recovers iron, and flotation process recovers sulfide or apatite.In general, the combined processes of weak magnetic separation-flotation process of polymetallic magnetite can be divided into weak magnetic separation-flotation and flotation-weak magnetic separation, the difference of which lies in the different direction of the continuum of magnetite and sulfide.For the weak magnetic separation-flotation process flow, the contiguous body mainly enters the iron concentrate; for the flotation-weak magnetic separation process flow, the conjoined body mainly enters the sulfide concentrate. Therefore, under the same grinding particle size, the first float and then magnetic process process can obtain iron concentrate with lower sulfide content and sulfide concentrate with higher recovery rate.
According to the types of iron-bearing minerals, common iron ore can be divided into magnetite, hematite, vanadium-titanium magnetite, limonite, siderite and mixed ore consisting of two or more of these iron bearing minerals. Among them, magnetite-hematite is a common mixed ore, and its beneficiation usually adopts a combined process flow composed of multiple beneficiation methods.
The single magnet-hematite is mostly fine-grained; the gangue mineral is mainly quartz, and some of it contains iron silicate. The proportion of magnets in the ore is gradually increases from the surface of the deposit to the deep part. The following two beneficiation methods are commonly used for selection:Weak magnetic separation, gravity separation/flotation/strong magnetic separationThe combined process of using weak magnetic separation to recover magnetite and then gravity separation, flotation or strong magnetic separation process to recover weak magnetic iron mineral.Production practice shows that for the weak magnetic separation-flotation process, the flotation method can be placed after the weak magnetic separation according to the nature of the ore and the actual conditions of the beneficiation plant, so as to ensure stable production indicators and save costs.
The iron minerals in polymetallic magnetite are mainly magnetite and hematite or siderite, medium and fine-grained; gangue minerals are mainly silicate and carbonate minerals or fluorite, etc., and the accompanying components include apatite , pyrite, chalcopyrite and rare earth minerals.The sorting of polymetallic magnetite is relatively complicated. Generally, the combined process consisting of weak magnetic separation and other mineral separation methods is used, that is, the weak magnetic separation method is used to recover the magnetite first, and then the gravity separation, flotation or strong magnetic separation method is used to recover weak magnetic iron minerals, and the associated components are final recovered by flotation.The above is the common magnetite beneficiation method. For magnetite beneficiation, it is recommended to tailor the process to suit your own through the beneficiation test, and rationally select the appropriate magnetite beneficiation method according to the final beneficiation test report.