CN102304623B - A method and equipment for reducing and depleting copper blowing slag - Google Patents

Abstract

The invention relates to a copper blowing slag depletion treatment method and equipment. The PS converter is transformed into a reduction converter with fuel injection into the furnace for heat preservation and reductant injection into the molten pool. The molten blowing slag is loaded into the furnace from the furnace mouth of the reduction converter, and the air is injected from the combustion lance set on the end wall of the reduction converter. The mixture with fuel is sprayed into the furnace to adjust the temperature, and the furnace temperature is controlled at 1200°C to 1300°C. The sulfur-containing coal-based reducing agent is sprayed into the furnace from the tuyere of the reducing converter, and the ratio of Fe/SiO ₂ in the slag is controlled at From 1.3 to 1.8, the Cu ₂ O in the slag is phase-transformed into Cu ₂ S and reduced to the end point, the slag is discharged from the furnace mouth, the slag with low copper content is separated from slag and matte, and the melt with high copper content is returned to the converter for blowing. The copper in the slag changes into matte, and the melting point and viscosity are improved, which is conducive to the precipitation and separation of matte from the slag, and improves the direct copper recovery rate of the blowing process and the recovery rate of copper pyrometallurgy.

Description

A method and equipment for reducing and depleting copper blowing slag

technical field

The invention relates to a method for reducing and depleting copper blowing smelting slag, which belongs to the technical field of nonferrous metal metallurgy.

Background technique

The current pyro-smelting process of copper sulfide concentrate is: copper concentrate smelting to produce copper matte → copper matte blowing to produce blister copper → blister copper pyro-refining, electrolysis to produce refined copper (Cu﹥99.95%). The equipment used for blowing copper matte into blister copper includes PS converter, flash furnace, top-blown furnace, continuous blowing reverberatory furnace, Mitsubishi continuous blowing furnace, etc. No matter which blowing method is used, it must be produced while producing blister copper. Output blowing slag. The copper content of blowing slag is relatively high (Cu﹥2%), and the magnetic iron oxide (Fe ₃ O ₄ ) content is usually 20% to 50%, and most of the copper is chemically dissolved in the slag in the form of oxide. There are currently three processes for recovering copper from blowing slag: slow cooling flotation method, electric furnace depletion method, and water quenching and smelting batching method. The slow cooling flotation process requires enough space to build a slow cooling field and a grinding and flotation production line. If the proportion of copper in the slag is chemically dissolved, the recovery rate of copper is not high, and the copper grade of the slag concentrate is usually not high, and the A large amount of gangue components are brought back to the process, and the tailings have fine particle size and large specific surface area, the activity of harmful metals in the tailings is high, and the cost of harmless storage is high; the electric furnace dilution method is to put the blowing slag into the electric furnace In, and then put in reducing agent and vulcanizing agent at the same time to reduce Fe ₃ O ₄ to slagging reaction and copper vulcanization reaction. Regardless of whether the reducing agent used in the electric furnace is solid, liquid or gaseous, the kinetic conditions of reduction are not good, so the reduction rate of Fe ₃ O ₄ is low, the frozen layer at the bottom of the furnace is thick, and the furnace condition is deteriorated; The method is to water-quench the blowing slag into small particles, mix them with copper concentrate and flux, and put them into the smelting furnace to achieve the purpose of copper recovery. This method requires less equipment and the process is simple. The main disadvantage is that it leads to fuel consumption in the smelting process. The ratio increases greatly, the blowing slag added is difficult to melt during the normal smelting process, the properties of the smelting slag deteriorate, and mechanical inclusions are formed, resulting in high copper content in the smelting slag waste and subsequent processing difficulties.

Contents of the invention

The purpose of the present invention is to change the defects of the existing blowing slag depletion treatment technology, and provide a reduction and depletion method and (converter) equipment for transforming the P-S converter into a temperature adjustment function and a solid reducing agent sprayed into the molten pool.

In view of the deficiencies in the current blowing slag dilution method, and in view of the adjustment of output or the change of blowing process in many copper smelters, it is possible to use P-S converter to dilute blowing slag through transformation or new side-blowing depletion furnace. It has the advantages of low investment, low renovation cost, good dilution effect and low operation cost. The invention provides an effective method and equipment for the dilution treatment of blowing slag.

The method of the present invention is to put the slag produced in the process of blowing copper matte into blister copper - blowing slag into the reduction converter, control the temperature of the furnace at 1200 ° C to 1300 ° C, and _mainly The following reaction occurs:

2Fe ₃ O ₄ + 3SiO ₂ + C=3(2 FeO·SiO ₂ )+CO ₂

2Fe ₃ O ₄ + 3SiO ₂ +2CO=3(2 FeO·SiO ₂ )+2CO ₂

C+H ₂ O=CO+H ₂

CO ₂ +C=2CO

2Cu ₂ O+2FeS+SiO ₂ =2Cu ₂ S + 2FeO·SiO ₂

Due to the existence of the above reaction, Fe ₃ O ₄ with high melting point and high specific gravity in blowing slag is eliminated, the viscosity and melting point of slag are reduced, which is beneficial to the separation of slag and matte, and the phase of copper is transformed into Cu ₂ which is incompatible with slag. S, put the blowing slag adjusted by the slag type into the electric heating front bed or the settling electric furnace for sedimentation and separation, and the waste slag with a copper content of less than 0.4% can be obtained. The present invention is accomplished by improving the PS converter.

The tuyere of the original P-S converter is horizontal, and the distribution of the jet of compressed air in the molten pool is only suitable for the blowing of copper matte. Whether it is the first cycle of blowing or the second cycle of blowing, the specific gravity of the blowing product is greater than that to be reacted The specific gravity of the material, so as the blowing progresses, the reactant floats into the injection area, and there is no blowing "dead zone". If the original tuyere is used as the injection port of the solid reducing agent, the blowing slag at the bottom cannot float up into the injection area because the specific gravity of the reactant is greater than the specific gravity of the product during the depletion process of the blowing slag, and there must be a depletion "dead". area", so the reducing agent injection port should be moved down. In order to save the transformation cost, the original process air pipeline facilities are retained, and the position of the outer wall of the tuyere remains unchanged, and the outlet is formed from the inner wall of the refractory brick at an angle of 10° to 30° downwards, so that the reducing agent is sprayed into the molten pool with the compressed air. The injection zone is formed close to the bottom of the furnace body, and there is no undisturbed quiescent zone during the depletion process. The invention transforms the traditional P-S converter with the functions of oxidative slagging (first cycle) and interactive reaction copper making (second cycle) into a reducing furnace with the functions of injecting fuel into the furnace for heat preservation and injecting solid reducing agent into the molten pool from the tuyere. Converter.

The P-S converter of the present invention retains two tuyeres (36 tuyeres for a 60-ton converter, and 54 tuyeres for a 100-ton converter). These two tuyeres are symmetrically located on both sides of the furnace body, and are 1.5 to 2.1 meters away from the end wall respectively. The two tuyeres are the injection inlets of the coal-based reducing agent), the tuyere at the entrance of the outer wall is inclined downward at an angle of 10° to 30°, and an outlet is formed from the inner wall of the refractory brick; an opening is opened on the end wall of the converter, and a combustion spray gun is set (the Fuel oil or gas or coal and air are mixed in the burner and sprayed into the furnace); different nozzles and universal joints can be set according to different fuel combinations to ensure that the nozzles and the furnace body rotate together;

Shrink the furnace mouth of the original converter, and add an insulation layer to the refractory material built on the foundation to reduce the heat loss of the converter reduction operation.

Reduction smelting:

The molten blowing slag is loaded into the furnace from the furnace mouth of the reduction converter. According to the content of iron and silicon dioxide in the slag, the Fe/ _SiO2 ratio in the slag is controlled at 1.3-1.8, and the insufficient amount of _SiO2 is added from the furnace mouth. The mixture of air and fuel is sprayed into the furnace from the combustion lance installed on the end wall of the reduction converter, the temperature of the melt is controlled at 1200°C to 1300°C, and the sulfur-containing coal-based reducing agent is sprayed with compressed air or nitrogen from the tuyere of the reduction converter. into the slag, the magnetic iron oxide in the blowing slag is reduced to slagging reaction, and at the same time, the Cu ₂ O in the slag is phase-transformed into Cu ₂ S. Reduction to the end point, the rotating furnace body slag is discharged from the furnace mouth, the slag with low copper content is sent to the conventional subsidence electric furnace for slag and matte separation with the slag bag, and the high copper content melt is returned to the converter for blowing.

The injected fuel is one or more of bituminous coal, anthracite or coke in solid fuel, or one or more of gas or natural gas in gaseous fuel, or heavy oil and diesel oil in liquid fuel , one or more of coal tar.

In order to meet the process control requirements of different reduction stages, different reducing agent injection gas sources can be freely switched during the reduction smelting process.

Compared with the prior art, the present invention has the following advantages:

(1) Adjust the combustion lance and tuyere angle of the P-S converter, economically transform it into a reduction converter, and the transformation cost is low; even if a new reduction and depletion furnace is built, the investment cost is not high. The coal-based reducing agent is sprayed into the molten pool from the inclined side tuyeres with compressed air, the kinetic conditions of the reaction are good, the reaction time is short, it is not easy to produce furnace knots and block the tuyeres, and the operation rate is high.

(2) Through reducing slagging, Fe ₃ O ₄ with high melting point and high specific gravity in blowing slag is eliminated, the viscosity and melting point of slag are reduced, which is conducive to the separation of slag and matte, and the phase of copper is transformed into a phase that is incompatible with slag. Cu ₂ S, the blowing slag adjusted by the slag type is put into the electric heating front bed or the sinking electric furnace for sedimentation and separation, and the waste slag with a copper content of less than 0.4% can be obtained; and the copper content of the melt at the bottom of the reduction and depletion furnace is relatively low High, it can be directly returned to the blowing furnace to increase the direct yield of the blowing furnace.

(3) The dilution operation is one-time feeding and one-time discharging, without frequent shaking of the converter, and less flue gas escape; compared with heavy oil, natural gas, and liquefied petroleum gas as reducing agents, the advantages of coal-based reducing agents are low cost, The reduction rate is fast, and the reduction process does not emit black smoke.

Description of drawings

Figure 1 is a schematic diagram of the structure of the spray gun and the tuyere before the conversion of the converter.

Fig. 2 is a schematic structural view of the newly added combustion lance and insulation layer of the converter of the present invention.

Figure 3 is a schematic diagram of the furnace mouth structure before and after the transformation of the converter.

Fig. 4 is a B-B sectional view in Fig. 3 .

Fig. 5 is a structural schematic view of the converter reducing agent spray gun and furnace mouth of the present invention.

Fig. 6 is a cross-sectional view of A-A in Fig. 5 .

In the figure, 1—increased insulation layer; 2—combustion lance; 3—the furnace mouth boundary after converter transformation; 4—the furnace mouth boundary before converter transformation; 5—reductant spray gun insertion port; 6—reductant injection after transformation aisle.

Detailed ways

Example 1:

For a copper smelter with an annual output of 150,000 tons, a 60-ton PS converter will be transformed. A fuel spray gun is installed on the end wall of one side of the converter. The combustion capacity of the spray gun is designed according to the fuel supply of 100kg-500kg/h; the refractory material of the converter mouth is increased by 100mm insulation layer; 1.6 meters, the position of the air outlet on the inner wall of the refractory brick is moved down, forming a 14° inclined downwardly inserted reducing agent injection channel. Put 50 tons of molten blowing slag containing 3.2% Cu, 46% Fe ₃ O ₄ , and Fe/SiO ₂ of 1.63 into the reduction converter, inject diesel to keep the furnace temperature at about 1250°C, and inject coal-based reducing agent ( 65% fixed carbon, 18% volatile matter, 1.5% sulfur, and particle size less than 5mm) enter the molten pool, the injection rate of the reducing agent is controlled at 15kg/min per gun, and the compressed air volume for transporting the reducing agent is 300Nm ³ /h· With only one gun, the reduction takes 34 minutes to the end, consuming 316kg of diesel and 1010kg of reducing agent. Rotate the furnace body to pour the reduced slag from the furnace mouth into the slag bag and send it to the subsidence electric furnace. After sedimentation and separation of the slag matte, the obtained waste slag contains 0.34% Cu and 3.55% magnetic iron oxide. The recovery rate of copper is 89.4%.

Example 2

For a copper smelter with an annual output of 250,000 tons, a 100-ton PS converter will be transformed. A coal-fired spray gun is installed on both sides of the converter, and the combustion capacity of the spray gun is designed according to the supply of coal (low calorific value 28.5MJ/kg) 180kg-560kg/h per gun; the refractory material at the converter mouth is increased 100mm insulation layer; there are two tuyeres on the converter, the center of the tuyere is 1.9 meters away from the end wall, and the position of the air outlet on the inner wall of the refractory brick is moved down, forming a 17° angled downward insertion reducing agent injection channel. Put 100 tons of molten blowing slag containing Cu 3.8%, Fe ₃ O ₄ 44%, and Fe/SiO ₂ 1.5 into the reduction converter, inject coal to keep the furnace temperature at about 1250°C, and inject coal-based reducing agent from the tuyere (68% fixed carbon, 17% volatile matter, 1.6% sulfur, and particle size less than 5mm) enter the molten pool, the injection rate of the reducing agent is controlled at 27kg/min per gun, and the compressed air volume for transporting the reducing agent is 540Nm ³ /h ·With only one gun, the reduction takes 36 minutes to the end, consuming 912kg of coal and 1960kg of reducing agent. Turn the furnace body to pour the reduced slag from the furnace mouth into the slag bag and send it to the subsidence electric furnace. The slag and matte are separated by sedimentation, and the obtained waste slag contains 0.36% Cu and 3.41% magnetic iron oxide. The recovery rate of copper is 90.5%.

The injected fuel can be one or more of bituminous coal, anthracite or coke in solid fuel, or one or more of coal gas or natural gas in gaseous fuel, or heavy oil in liquid fuel, One or more of diesel oil and coal tar.

If the ratio of Fe/SiO ₂ in the molten blowing slag is less than 1.3 to 1.8, the flux SiO ₂ can be supplemented to the required amount.

Claims (2)

1. A method for copper blowing slag depletion treatment, which is characterized in that the slag produced in the process of blowing copper matte into blister copper - blowing slag is put into the reduction converter, and the mixture of air and fuel is sprayed into the furnace, Control the furnace temperature at 1200°C to 1300°C, and carry out the reduction reaction under the action of coal-based reducing agent and flux SiO ₂ ; control the ratio of Fe/SiO ₂ in the slag to 1.3 to 1.8, and change the phase of Cu ₂ O in the slag to Cu ₂ S is reduced to the end point, the slag is discharged from the furnace mouth, the slag with low copper content is separated from slag and matte, and the melt with high copper content is returned to the converter for blowing. 2. The method for copper blowing slag depletion treatment according to claim 1, characterized in that the injected fuel is one or more of bituminous coal, anthracite or coke in solid fuel, or is One or more of natural gas or natural gas, or one or more of heavy oil, diesel, and coal tar in liquid fuels.

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