RU2410446C1 - Method of mineral ore processing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to method of mineral ore processing. proposed method comprises heating the plasma-forming gas by electric arc and plasma chemical thermal treatment of ores by mixing heated gas with ore crushed in rector hosing. Then, mix of heated gas and processed ore are separated and cooled down. Note here that mix of heated gas and processed ore is separated by inertial forces originating on forming the clearance between vertical flat partition lower edge and reactor housing bottom, prior to discharging gas and ore from the reactor housing.

EFFECT: higher efficiency of plasma chemical reactor, reduced capital and operating costs.

1 tbl, 1 dwg, 1 ex

Description

The invention relates to a method for processing mineral ores before flotation. This method can also be used to recover pure metals from metal oxides (molybdenum, lead, tin) and to free sulfide minerals from sulfur.

A known method of processing sulfide ores described in patent 2229938 (RU IPC ⁷ B03B 7/00, C22B 3/00, C22B 4/00, publ. 06/10/2004), which is carried out by grinding the original ore to a particle size of not more than 0.25 mm, and then carry out flotation separation into non-metallic minerals and industrial product. Dehydrated to a residual moisture content of not more than 2%, the intermediate product is sent for further processing, which is carried out by feeding it in a neutral gas stream to a plasma-chemical reactor, where high-speed, high-temperature heating of the finely dispersed phase of the intermediate product is carried out in a neutral gas stream. After the heated mixture exits from the plasma chemical reactor, it is subjected to sharp cryogenic cooling, followed by separation of elemental sulfur and obtaining a collective powder concentrate.

The technical result of the known invention is to reduce the cost of labor and energy costs during enrichment, as well as significantly reduce harmful emissions into the atmosphere and improve the environmental situation in the ore processing area.

What is common in the method indicated and proposed by us is mixing gas with crushed ore, heating a mixture of gas and ore, cooling gas and processing products.

With this processing method, the separation of gas and ore is also carried out only after they have been quenched, which is due to the long contact time of the processed material and gas.

Patent 2064516 (RU IPC ⁶ C22B 23/02 2064516, published July 27, 1996) describes a method for processing oxidized nickel ores, which includes feeding ore and calcareous fluxes in countercurrent with high-temperature exhaust gases, smelting with a carbon-containing fuel to produce a melt. The resulting melt enters the plasma-arc zone of the furnace, where it is treated with neutral gas plasma with a solid reducing agent in the amount of 0.04-0.45 by weight of the starting material. For sulphidation of the melt, troilite concentrate is used, supplied in an amount of 0.02-0.03 by weight of the starting material.

The purpose of the known invention is to increase the extraction of Nickel and cobalt from the processed material, as well as the elimination of emissions of sulfur dioxide in the atmosphere.

The common thing in the method indicated and proposed by us is mixing gas with ground ore, heating a mixture of gas and ore and treating with plasma.

The disadvantage of this method is the large contact time of the plasma with the melt.

The closest (prototype) in technical essence and the achieved result to the patented method is the plasma-chemical method of ore processing described in [A.L. Suris. Plasma-chemical processes and devices. Publishing house "Chemistry", 1989, p.8-10]. The known method of processing ore is carried out in a plasma-chemical reactor, which consists of a cathode, insulator, anode, mixing device, reaction channel, quenching device, heat exchanger, filter. An electric arc is formed between a cathode made of a refractory material and a water-cooled copper anode made in the form of a nozzle. Plasma-forming gas (air, hydrogen) is selected depending on the type of process being carried out (heat treatment of ore before flotation, reduction of metal oxides). Passing through the discharge zone, the gas is heated, ionized, and flows into the reactor in the form of a plasma jet with a mass-average temperature of 2000-10000 K. The jet enters the mixing chamber of the reactor, where raw materials are introduced into it. In the reaction channel there is a chemical interaction of the reactants with the formation of the target products. The walls of the reactor are cooled with water. The quenching device and heat exchanger are designed to cool the reaction products. The filter separates gases from solid particles.

A gas-dust mixture flows from the reactor to the heat exchanger at a high speed, which causes increased gas-abrasive erosion of the walls of the tubes of the heat exchanger, resulting in increased operating costs. In addition, this method of processing ore is characterized by an unreasonably long contact time of high-temperature gas and the processed material (up to 5 s), which leads to a decrease in reactor productivity and the quality of processing of raw materials.

The objective of the invention is to develop a more efficient plasma-chemical method for processing mineral ores with minimal capital and operating costs for cooling products in a heat exchanger, which allows to increase the productivity of the reactor in which this method is carried out, and reduce capital and operating costs.

The technical result of the invention is:

- increasing the productivity of the plasma chemical reactor for ore, while improving the quality of the product;

- reduction of capital and operating costs for cooling products in the heat exchanger;

- reducing the contact time of high temperature gas and the processed material;

- reduction of ore losses with exhaust gases.

The elimination of these drawbacks and the achievement of a technical result from the implementation of a method for processing mineral ores, including heating a plasma-forming gas by an electric arc, plasma-chemical heat treatment of ores by mixing heated gas with crushed ore in a reactor vessel, separation of a mixture of heated gas and processed ore, and their cooling, achieve that separation of the mixture of heated gas and processed ore is carried out by inertial forces arising from a change in the direction of movement of the mixture due to the formation of the gap between the lower edge of the vertically mounted flat walls and the bottom of the reactor vessel, before they are withdrawn from the reactor vessel.

A comparative analysis of the prototype and the claimed invention shows that common signs are the heating of a plasma-forming gas by an electric arc, plasma-chemical heat treatment of ores by mixing heated gas with ground ore in the reactor vessel, separation of the heated gas and treated ore mixture and their cooling.

A distinctive feature of the claimed invention is that the separation of the heated gas mixture and the processed ore is carried out by inertial forces arising from a change in the direction of movement of the mixture due to the formation of a gap between the lower edge of the vertically mounted flat partitions and the bottom of the reactor vessel, before they are withdrawn from the reactor vessel.

A new method of ore processing can be used to recover pure metals from metal oxides (molybdenum, lead, tin), to free sulfide minerals from sulfur, and also to prepare ore for flotation.

With the known method of processing ore from the lower part of the reactor, a high-temperature gas and dust medium is supplied, which is fed to the heat exchanger tubes at a high speed, this is associated with the aforementioned disadvantages of the prototype.

The proposed method allows to eliminate the disadvantages of the known method by separating gas and solid particles, which is carried out directly in the reactor vessel, and not after the heat exchanger, as in the known method. The same measure can reduce the contact time of gas and solid particles in the reactor and, as a result, increase the productivity of the reactor and improve the quality of the product. The separation of gas and solid particles in the reactor vessel with a new method of processing ore can be carried out, for example, due to inertial forces arising from a sharp change in the direction of motion of the dust and gas environment. To this end, it is proposed to install a vertical flat baffle 10 in the reactor (see the drawing) with the formation of a gap between the lower edge of the baffle and the bottom of the reactor vessel. Gas at the outlet of the reactor through a pipe (bubbler) 9 is sent to a container of water 11, where it is cooled and trapped residual solid particles. The wet method of gas purification from particles, carried out in the tank 11, is more effective than the previously used dry cleaning method. From tank 11, water with solid particles enters the flotation. Solid particles (processed ore) from the lower conical part of the reactor vessel also go to cooling and then to flotation.

The essence of the proposed method is illustrated by the following example and the drawing, which schematically shows a reactor, a plasma torch and a tank for wet gas purification.

The reactor includes a housing 1, a cover 2, a pipe 3, a coupling 4, a plasma torch 5, a gas supply device, a loading funnel 6, a protective shield 7, a device for unloading the processed product 8, a gas outlet device 9 (bubbler), a vertical flat partition 10, a container with water 11. The reactor vessel 1 is made in the form of a lined steel structure made of sheet metal, all the components and mechanisms of the reactor are mounted on it. In the upper cover 2 of the housing 1, a pipe 3 is welded with a thread on the end. A coupling 4 is screwed onto the threaded part of the pipe, into which a plasmatron 5 is inserted. The housing walls are protected by a lining. The shield 7 is designed to protect service personnel from high temperatures during the removal of the plasma torch head from the pipe 3. Through the device 8, the processed product is unloaded. The reactor also provides for cooling the walls of the vessel with water.

A new plasma-chemical method for processing ore is as follows. The plasma-forming gas is first heated by an electric arc, then mixed with crushed ore, then after heat treatment, the ore and gas are separated, and then the products are cooled. The method can be carried out in a reactor, which is a cylindrical tank (1400 mm high and 400 mm in diameter) with a conical bottom (see drawing). The ore productivity of this reactor is 53 t / h. Plasma-forming gas is selected depending on the type of process being conducted. After supplying electric energy, water, gas and the readiness of the system, ignition of the plasma torch 5 is turned on. Clutch 4 controls the position of the flame in the reaction zone using a thread on the pipe 3. The average temperature in the reactor is 5800-6000 ° C. Thus, the material loaded into the funnel 6 can be fed to different sections of the flame. During the operation of the reactor in the vessel create excess pressure (2.5 · 10 ⁵ PA). In order to prevent ore losses, a water trap with a bubbler 9 is installed. To separate gas from solid particles due to inertia forces, a vertical partition 10, which is a porous metal fabric or porous ceramic, is welded in the reactor vessel 1. Between the lower edge of the partition 10 and the bottom of the housing, a gap is formed for the passage of gas. The separation of gas from solid particles is carried out directly in the reactor vessel due to inertial forces. Solid particles settle in the conical bottom of the reactor, and the gas changes the direction of motion by 180 °, goes around the partition 10 and enters the space between the partition 10 and the wall of the vessel, from where it is taken into a container of water. A certain part of the ore in the form of dust rises up between the wall of the tank and the partition 10, then through the bubbler 9 of the hydraulic lock it enters the tank with water 11, where the particles are deposited and sent to flotation, and the gas is cleaned into a cyclone. This eliminates the loss of ore with escaping dust. The removal of processing products is carried out through the unloading device 8.

Example

The implementation of the patented method is shown on the example of the preparation of mineral ore for flotation. The ore used is pre-crushed to a size of +2 mm, after which it is fed into the plasma-chemical reactor described above, in which it is in contact with air plasma. The duration of contact (duration of plasma-chemical treatment) is 0.5 sec. The temperature of the air plasma depends on the type of plasma-forming gas, in this case air, and is maintained in an appropriate interval. Temperature, operating current and voltage are maintained in values that ensure the optimal plasma-chemical treatment of ore. During processing, an excess pressure (2.5 · 10 ⁵ Pa) is created in the reactor vessel. The productivity of the pilot plant for ore is 53 t / h.

The effectiveness of the plasma-chemical processing of ore was judged by the kinetics of grinding the ore processed by the present method, by the disclosure of a useful mineral and the content of free grains of a valuable component in the pulp.

The initial ore (before plasma treatment) and plasma-treated ore are fed to a grinding unit to bring the particle size to a design class of +0.63 mm, after which the target product is flotated from non-metallic minerals. The kinetics of grinding are presented in the table.

From the above results it is seen that the inventive method of processing ore provides a significant reduction (from 12 to 6 minutes) the duration of the subsequent grinding of the ore and a doubling of the productivity of the grinding unit. It has been convincingly shown that when grinding ore processed by plasma in the first 6 minutes, the yield of the optimal size class increases by 15% and the yield of sludge (reduction of ore losses) by 8% decreases by the end of grinding.

As a result of studies, it was found that the processing of mineral ore by the present method provides the best disclosure of a useful mineral and an increase of 1.5-2.0% in the pulp content of free grains of a valuable component (quality improvement). This reduces the duration of contact of the ore with the plasma (0.5 sec), which prevents the possibility of melting valuable components. The latter has a positive effect on the quality of the target products and their output.

The contact time of the ore particles with the plasma stream in the new method compared with the known method can be reduced from 1-5 seconds (processing time 1-5 seconds leads to the melting of lead and tin) to 0.1-0.5 seconds due to gas separation and particulate matter directly in the reactor vessel. This allows you to increase the productivity of the reactor in ore by almost 20-30%, and the quality of ore processing is improved.

Table The kinetics of grinding of the original and plasma treated ore The grinding time, min Ore Source Plasma treated Yield, wt.% Grade + 0.63 mm Sludge Grade + 0.63 mm Sludge one fifteen 3 25 four 2 27 5 fifty 9 four 60 12 85 fifteen 6 85 fifteen one hundred 22 8 94 22 - - 10 97 25 - - 12 one hundred thirty - -

Claims (1)

A method of processing mineral ores, including heating a plasma-forming gas by an electric arc, plasma-chemical heat treatment of ores by mixing heated gas with ground ore in a reactor vessel, separating the heated gas and treated ore mixture and cooling them, characterized in that the heated gas and treated ore mixture are separated by inertial forces arising from a change in the direction of movement of the mixture due to the formation of a gap between the lower edge of the vertically mounted flat partitions and the bottom to Pusa reactor prior to withdrawal from the reactor vessel.

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