Metal Ore Dressing Mysteries

(A) Definition and role of metal ore dressing

1. Definition of beneficiation

The earliest English explanation of beneficiation is Ore Dressing or concentration, which means ore enrichment. Subsequently extended to the mineral processing, the English for Mining process. beneficiation is the use of mineral physical or physicochemical properties of the difference, with the help of different methods, the useful minerals with the useless minerals separation, the useful minerals as far as possible with each other * * * born separated and enriched into a separate concentrate, to exclude the smelting and other processing harmful impurities, improve the quality of the product of the beneficiation of the product, so as to fully, Reasonable, economic utilization of mineral resources.

Minerals are natural elements and natural compounds produced in the earth's crust as a result of natural physicochemical or biological action, such as gold, silver, copper natural elements and pyrite, chalcopyrite, galena and other natural compounds. These elements and compounds have their own physical properties, such as particle size, shape, color, luster, density, coefficient of friction, magnetism, electrical properties, radioactivity, surface wettability and so on. These different properties provide the basis for different beneficiation methods.

2. The role and status of beneficiation

Nature is extremely rich in mineral resources, but, in addition to a small number of rich ores, the general content is low, for example, many iron ores containing iron is only 20% ~ 30%; copper ore containing copper less than 0.5%; lead-zinc ore in lead-zinc content is less than 5%; beryllium ores of beryllium oxide content of 0.05% to 0.1%; such ore Direct smelting, extremely uneconomical. General metallurgy on the content of the ore has certain requirements. Such as iron ore in the iron content of the minimum shall not be less than 45%; copper ore in the copper content of the minimum shall not be less than 12%; lead ore containing lead shall not be less than 40%; zinc ore containing zinc shall not be less than 40%; beryllium oxide content of not less than 8%. For the extracted ore in the smelting before, must go through the beneficiation process, the content of the main metal minerals will be enriched a few times, dozens of times and even hundreds of times to meet the requirements of the smelting process.

Through the means of beneficiation for smelting to provide "concentrate", reduce the amount of smelting materials, and greatly improve the technical and economic indicators of smelting. In the beneficiation process, a large number of waste rock is excluded, reducing the amount of slag, on the one hand, reduce energy consumption and transportation costs, but also correspondingly reduce the loss of metal in the slag, greatly improving the recovery rate of smelting. For example, a smelter will increase the copper concentrate content by 1%, can produce 3135 tons of crude copper per year. A steel company will increase the iron ore concentrate content of 1%, the blast furnace output increased by 3%, saving limestone 4% to 5%, reducing the amount of slag 1.8% to 2%. At present, China's requirements into the furnace iron ore magnetite content of 65% or more, if the iron ore concentrate content of 68% or more, you can use direct steelmaking process, greatly simplifying the smelting process.

Through the beneficiation process can reduce the smelting of raw materials in the harmful elements of the harm, turn harm into benefit, comprehensive recovery of metal resources. Ore in nature often contains a variety of useful components, for example, copper, lead, zinc and other non-ferrous metals are often **** born or accompanied by the same deposit; iron has a single iron ore, but also iron-copper, iron-sulfur, vanadium-titanium-iron and other **** born ore. Smelting process of raw materials in some *** raw or associated elements, often regarded as harmful impurities. For example, copper refining raw materials containing lead, zinc are harmful impurities. Iron refining raw materials containing sulfur, phosphorus and other non-ferrous metals are harmful impurities. But these impurities in advance through the beneficiation process to make the separation of separate enrichment, respectively, smelting, change the harm for the benefit.

Beneficiation is also used as an intermediate process in the smelting process, used to improve the total economic benefits of beneficiation, smelting two processes. For example, China's Jinchuan Nonferrous Metals Company smelter's existing production process is a copper-nickel mixed concentrate with electric furnace melting, converter blowing, output of high ice nickel, after slow cooling, and then crushing and grinding, flotation to obtain copper concentrate and nickel concentrate, magnetic separation to get the alloy. Thereafter, they enter their respective smelting systems to extract metallic copper, nickel and precious metals.

Mineral processing is metallurgy, chemical industry, building materials and other industrial sectors essential and extremely important part. Beneficiation technology development, greatly expanding the industrial raw material base, so that those who previously because of the content is too low or complex composition and can not be applied in the industrial deposits into useful deposits.

Nearly 20 years, with the rapid development of science and technology and economic construction, the demand for mineral resources is increasing day by day, the mining of mineral resources doubled, the cycle is getting shorter and shorter, easy to mine easy to choose a single rich ore is getting less and less, embedded in the fine grain size, low content of difficult to select the composite minerals are getting more and more mining, the processing of minerals in the environmental protection requirements are getting higher and higher, these are required by the beneficiation method to solve.

(B) beneficiation methods

Currently used beneficiation methods are mainly re-election, flotation, magnetic separation and chemical beneficiation, in addition to this there are electric election, hand-election, friction beneficiation, photoelectricity beneficiation, radioactive beneficiation and so on.

Gravity beneficiation (referred to as gravity beneficiation), is based on the different density of minerals and their different settling speed in the medium (water, air, heavy media, etc.) for the sorting method, which is one of the oldest methods of mineral processing. This method is widely used to sort coal and ores containing platinum, gold, tungsten, tin and other heavy minerals. In addition, iron ore, manganese ore, rare metal ores, non-metallic ores and some non-ferrous metal ores are also selected by re-election method.

Magnetic separation, is based on the different magnetic properties of minerals for sorting method. It is mainly used for separating iron, manganese and other ferrous metal ores and rare metal ores.

Floatation beneficiation method (referred to as flotation method), is based on the mineral surface of the wetting of the different methods of mineral separation. At present, the flotation method is most widely used, especially fine-grained dipping ores with flotation processing effect is remarkable. For the separation of complex polymetallic ores, flotation is one of the most effective methods. At present, the vast majority of ores can be processed by flotation.

Chemical beneficiation method, based on the differences in the chemical properties of minerals and mineral components, the use of chemical methods to change the composition of minerals, and then use the corresponding method to make the purpose of component enrichment of mineral processing technology. At present, the effect of oxidized ore processing is very obvious, is also one of the effective methods of processing and comprehensive utilization of certain poor, fine, miscellaneous and other difficult to select mineral raw materials.

Electrowinning method is based on the different electrical properties of minerals to sorting method.

Hand-selected method is based on the mineral color and luster of the different selection method.

Friction beneficiation is a method of separating minerals by utilizing the difference in the coefficient of friction of the minerals.

Photoelectric beneficiation is a method of sorting minerals by utilizing the difference in intensity of reflected light from minerals.

Radioactive beneficiation is the use of natural and artificial radioactivity of minerals to sort minerals.

(C) beneficiation process

Beneficiation is a continuous production process, consists of a series of continuous operations, indicating that the continuous processing of ore process for the beneficiation process (Figure 6-7-1).

The ore beneficiation process is completed in the beneficiation plant. Regardless of the size of the beneficiation plant (small beneficiation plant processing dozens of tons of ore per day, large-scale beneficiation plant daily processing of up to tens of thousands of tons of ore or more), but regardless of how complex the process and equipment, generally include the following three most basic processes.

Preparatory operations before sorting: the general ore from the mining field ore size are larger, must be crushed and screened, grinding and grading, so that the useful minerals and vein minerals, useful minerals and unwanted minerals are separated from each other to achieve the separation of the monolithic, in order to prepare for the sorting operation.

Sorting operation: this is the key operation (or the main operation) of the mineral processing process. It is based on the different properties of minerals, using different beneficiation methods, such as flotation, re-election, magnetic separation, etc..

Product processing operations: mainly including concentrate dewatering and tailings treatment. Concentrate dewatering usually consists of three stages: concentration, filtration and drying. Tailings treatment usually includes storage of tailings and treatment of tail water.

Some beneficiation plants according to the nature of the ore and the need for sorting, in the sorting operation with washing, pre-waste (i.e., in the coarser particle size in advance of discharge part of the waste rock), as well as physical, chemical and processing operations, such as magnetization of hematite roasting and other operations.

(D) the application of mineral processing technology in Xinjiang mines

The application of mineral processing technology in Xinjiang can be traced back to ancient times, Xinjiang as far as 300 years ago, in the Altay region of the various ditches in the use of gold than the significant characteristics of gold from the sandy gold ore gold panning, which is the primitive prototype of reelection. However, before the establishment of New China, Xinjiang did not have a formal mineral processing plant, all are hand-selected and hand-panned manually, the production efficiency is extremely low, can only deal with the specific gravity of alluvial gold ore and hand-selected wolframite according to the color. After the founding of New China, Xinjiang mineral processing technology has made great development, magnetic separation technology is applied to iron ore mines, and a magnetic separation plant with an annual processing capacity of 800,000 tons has been built, which constantly provides high-quality iron ore concentrates for iron and steel enterprises. Flotation is applied to lead-zinc, copper and gold mines, and we have successively built Kangsu lead-zinc flotation plant, Kharatongke copper-nickel flotation plant and Hatu gold flotation plant, which have promoted the development of non-ferrous industry in Xinjiang. Re-election, flotation, magnetic separation is jointly applied to rare metal mines in Altay region of northern Xinjiang, providing lithium, beryllium, tantalum, niobium and other rare metal resources needed for China's early national defense construction. The following are currently representative of the mineral processing plant in Xinjiang.

1. Kangsu Lead-Zinc Ore Flotation Concentration

Kangsu Concentration Plant is the first mechanized flotation plant in Xinjiang, the construction of which began in 1952, with a designed production scale of 250 tons / day, and put into operation in 1954. The plant was designed with the participation of experts from the former Soviet Union, and it mainly processed galena and sphalerite from Sharitash in Kashgar area in the early stage, and began to process oxidized lead and zinc ores from Wulagan in 1961. When the plant was first put into operation, it adopted the process and pharmaceutical system designed by the Soviet experts to carry out flotation, which used cyanide and zinc sulfate as inhibitors for sphalerite, soda as pH adjusting agent, and a small amount of sodium sulfide was added to select the lead ore in priority before selecting the zinc minerals. This process did not achieve good economic indicators, most of the zinc ore was selected into the lead ore. Later, after our engineering and technical personnel and the Soviet Union experts **** the same efforts, through several technological transformation, in the process structure, technical parameters and production management of innovation and improvement. Part of the German-style flotation machine into the Soviet-style Mihanobel 5A-type flotation machine with a large inflatable air, the use of hydrocyclone instead of spiral classifier, strengthen the regrinding cycle of the middle ore, increase the zinc flotation time, reduce the zinc flotation slurry alkalinity, a reasonable control of the crushing size and the amount of ball loading, and the strict implementation of the technical operating procedures and technical supervision, and so on. All the indexes were steadily improved. Lead recovery rate increased from 71% to 90%, zinc recovery rate increased from 13% to 41%. The beneficiation process is shown in the flotation process flow chart (Figure 6-7-2).

2. Magnetite flotation beneficiation in Xinjiang Bayi Iron and Steel Plant

The Xinjiang Bayi Iron and Steel Plant was put into operation in 1989, with a design capacity of 800,000 tons/year, and mainly handles high-sulfur magnetite. After the ore is extracted from the mine, it is transported to the beneficiation plant, and after two stages of crushing and one stage of grinding, the ore slurry enters the flotation-magnetism workshop. The selected sulfur concentrate is sold to some chemical plants and fertilizer plants in Xinjiang, and the iron concentrate is used for pelletizing and sintering. After the tailings are concentrated, they are transported to the tailings storage by water separator pumps, and after drying, a part of the tailings becomes the raw material for iron correction of the West Region Cement Plant of BAGCO. Simple flotation and magnetic separation flow chart of Xinjiang Bayi Iron and Steel Plant (Figure 6-7-3).

3. Kerala Tongke copper-nickel mine flotation beneficiation

Kerala Tongke copper-nickel mine is currently the largest copper-nickel production base in Xinjiang, the first phase of the mine for the mining and metallurgical engineering, extracted from the extra-rich ore directly into the blast furnace smelting of nickel into a low ice, after a few years of production of the extra-rich ore is gradually reduced. In order to make full use of the mineral resources, in the second phase of the renovation of the preferred selection of copper-copper-nickel mixed flotation process, 900 tons of raw ore processing day.

The raw ore is lifted directly from the quarry to the ground through the shaft, and transported to the raw ore bin through the narrow rail, and the ore in the raw ore bin is sent to the intermediate bin by the belt conveyor through the group feeder. Through the heavy plate feeder and belt conveyor, it is sent to the autogenous mill for one stage of grinding, and the discharge from the autogenous mill is fed into the high weir double screw classifier which is in closed circuit with the lattice-type ball mill for the second stage of grinding. The overflow of the classifier is sent to the hydrocyclone group through the sand pump, and the settled sand enters into the overflow ball mill for three-stage grinding. The discharge from the third stage of grinding is combined with the overflow from the first stage of classifier, which is sent to the hydrocyclone group by sand pump, and the overflow from the cyclone flows into the mixing tank of the flotation plant, and then enters into the flotation operation after dosage. After the flotation adopts one copper roughing, one copper selection, one copper-nickel mixed flotation, one copper-nickel sweeping and three copper-nickel selections, the output of copper concentrate, copper-nickel mixed concentrate and tailings are sent to the dewatering plant respectively. Copper concentrate and copper-nickel mixed concentrate are dewatered and sent to the copper concentrate storage and smelter raw material storage respectively. The flotation tailings are dewatered by high efficiency thickener and then sent to the filling station of the mining site by pump Yang as filling materials. The simple beneficiation process flow chart of Kerala Tongke copper-nickel mine (Figure 6-7-4).

4. Hatu gold mine gold amalgamation-flotation beneficiation

Hatu mine is a famous rock gold origin in the history of Xinjiang, and started to be mined as early as in the Qianlong period, and the main method used is the clay re-election method, which crushes the extracted ore with a stone milling disk, and recovers the gold particles of large specific grains by panning. A large number of fine-grained gold can not be recovered, resulting in many gold miners serious losses.

In 1983, through experimental research, using "amalgamation - flotation - part of the roasting - cyanide" principle process, Hatu gold mine built the first modern gold production mine in Xinjiang, the daily processing of raw ore 100 tons. 1986, through the improvement of the ore milling - flotation - part of the roasting - cyanidation. In 1986, by improving the crushing process, a new flotation series of 100 tons/day was added, bringing the production capacity to 200 tons/day. Hatu gold mine amalgamated mercury flotation process flow chart (Figure 6-7-5).

The raw ore is transported from the mining plant to the raw ore silo by automobile, and the raw ore is crushed in one stage by the jaw crusher. Then it is transported to the cone crusher by belt conveyor for second stage crushing. After the crushed products are screened by circular vibrating screen, the screened minerals are transported to the powder ore bin by belt conveyor, and the screened minerals are returned to the cone crusher for re-crushing. Powder ore bin through the feeder and belt conveyor sent to the lattice ball mill grinding, grinding ore discharge self-flow through the silver-plated copper plate (commonly known as mercury plate) for mercury amalgamation operations, through the mercury adhered to the surface of the mercury plate adsorption of the monomer of the solubilization of the gold formation of the amalgam, and through the smelting of the recovery of part of the gold. After the slurry passes through the mercury plate, with high weir spiral classifier, the overflow enters the flotation process, and the returned sand enters the ball mill for regrinding. The flotation process adopts the flotation concentrate selected by one roughing, two selecting and one sweeping process. Flotation concentrate dehydration after roasting and smelting to get gold ingots.

5. Cocoa Tohai rare metal ore heavy, magnetic, electric, flotation joint beneficiation

Cocoa Tohai is famous for its large reserves of rare metals, many varieties, beryllium, lithium, tantalum, niobium, rubidium, cesium, zirconium, hafnium, and other rare elements in many ore zones have varying degrees of distribution, which results in the complexity and difficulty of beneficiation. After 10 years of repeated experimental research by many scientific and technological personnel, from manual beneficiation to single-mineral beneficiation, developed to the final heavy magnetic flotation joint beneficiation process, separated lithium concentrate, beryllium concentrate, tantalum and niobium concentrates, breakthroughs in this world-wide problem, and promote the development of mineral processing technology.

In 1953, in order to recover beryl and tantalum-niobium ore in the No. 3 vein of the northeast corner of the small open-pit quarry built a simple 30-meter-long hand-selecting room to improve the working environment of hand-selecting, and improve the efficiency of hand-selecting. In addition, in the No. 3 vein tailings pile near the construction of a 20 tons / day tantalum and niobium re-election plant, the use of rolling a section of crushing, jigging, shaking table, chute re-election, recovery of tantalum and niobium ores. 1957 ~ 1958, the tailings under the screen of the hand-selected, with a square spiral chute for enrichment, the output of annual output of lithium oxide concentrates close to 10,000 tons.

In 1963, after nearly 8 years of experimental research on mineral processing by scientific research institutes, the State Planning Commission approved the construction of 750 tons / day of mineral processing plant ("87 - 66" machine processing plant), integrated recovery of lithium oxide concentrate and tantalum and niobium concentrate. The process flow diagram of the plant (Figure 6-7-6). According to the characteristics of the Cocotocai Mine's pegmatite zone mining, the plant uses three systems to separate three types of ores (beryllium, lithium and tantalum-niobium ores). The combined beneficiation process is used to comprehensively recover the lithium-beryllium-tantalum-niobium minerals in the ore. Firstly, gravity-magnetism-electromagnetism beneficiation is utilized to select more than 50% (Ta,Nb)203 tantalum-niobium concentrates from the raw ore with only 0.01% ~ 0.02% (Ta,Nb)203 content, and then lithium-beryllium-priority flotation by alkali method is used to preferentially flotation lithium and then beryllium.

The continuous improvement of the CocoTokyo sea processing plant beneficiation process, so that China's granite pegmatite type ore tantalum-niobium, lithium, beryllium beneficiation process level into the world's advanced ranks.

6. The direction of development of mineral processing technology

In the United States, Japan, Germany and other countries on the development of mineral processing technology attaches great importance to the continuous progress and innovation of mineral processing technology to promote the development and comprehensive utilization of mineral resources in these countries along the sustainable development forward. In terms of mineral crushing, the United States developed ultra-fine crusher and high-pressure tumbler, reducing ball mill feed size, saving energy consumption. At the same time in the continuous study of applied electric field, laser, microwave, ultrasound, high-frequency oscillation, plasma treatment of ore on the impact of crushing and sorting. In mineral sorting, has been or is researching "a variety of force field" joint action of sorting equipment, and constantly introduce high technology into the field of mineral processing engineering, such as the introduction of superconductivity technology into magnetic separation, electrochemical and control technology into flotation, etc.. In the ore dressing process management, the process control process automation, and "expert control system" and "optimal timing control" combined to achieve according to the nature of the ore to adjust the control parameters, so that the whole process of ore dressing production process to maintain the optimal state.

With the rapid development of China's national economy, the demand for minerals continues to grow, beneficiation engineering technology is faced with resources, energy, environmental protection, the serious challenges and development opportunities. The following areas of technological innovation will be the future direction of development of mineral processing:

One is the research and development of high-efficiency pre-selection equipment, energy-efficient new grinding and sorting equipment, as well as solid-liquid separation of new technologies and equipment, significantly reduce the ore crushing solid-liquid separation process of energy consumption.

The second is to study the impact of various energy fields of pretreatment on the behavior of mineral crushing and sorting, the development and utilization of a variety of energy fields of pretreatment of new technologies to improve the crushing efficiency and sorting accuracy.

Third, the development of high-efficiency sorting equipment, high-efficiency and non-toxic new chemicals, focusing on the research of composite force field sorting equipment, a variety of components of the synergistic effect of the new chemicals, as well as the treatment of poor, fine, miscellaneous difficult to sort out the ores of the comprehensive sorting of new technologies.

Fourth, in the comprehensive utilization of ore research, the development of waste-free clean production process, strengthen the separation of minerals in the tailings, purification, ultrafine, modification of the research, so that it becomes the market needs of the product, for the transformation of the mineral materials industry to the mineral materials industry to provide new technologies.

Fifth, vigorously introduce high and new technologies into the field of mineral engineering, focusing on mineral bioengineering technology, electrochemical regulation and electrochemical control flotation technology, process automatic search for the best technology, as well as high-tech transformation of traditional industries, new technology research.

Sixth, strengthen the basic theory and mineral processing technology combined with the new fringe science research, promote the formation of a new generation of mineral sorting theory system, and derived from the emerging mineral sorting and purification technology.