CN112048625A - Lead-zinc oxide ore recycling harmless treatment system and method - Google Patents

Abstract

The invention relates to a system and method for the harmless treatment of lead-zinc oxide ore resources, belonging to the technical field of lead-zinc oxide ore treatment. The zinc ore is added from the preheating unit, and is directly contacted with the flue gas for preheating or indirectly heated by heat exchange, and then enters the precalciner. The zinc oxide dust produced by the reduction and volatilization of the rotary kiln is recovered after being enriched; the slag produced by the rotary kiln is cooled by the cooler to produce secondary hot air and low-temperature harmless slag, and the secondary hot air is sent to the precalciner and the material is dried. and waste heat boiler recycling, harmless slag can be used to produce building materials; the invention fully recycles and utilizes the waste heat of flue gas and slag, makes full use of the advantages of large specific surface area of powder, improves the rate of heat exchange and reduction and volatilization, and greatly improves the lead oxide The processing capacity of zinc ore and the utilization rate of heat energy reduce the production cost.

Description

A system and method for the harmless treatment of lead-zinc oxide ore resources

technical field

The invention belongs to the technical field of lead-zinc oxide ore treatment, and in particular relates to a system and method for the harmless treatment of low-grade lead-zinc oxide ore resources.

Background technique

The ore structure of lead-zinc oxide ore is complex, and the beneficiation is difficult, especially for low-grade lead-zinc oxide ores. At the same time, with the continuous development and utilization of high-quality lead and zinc resources, the efficient development and utilization of low-grade lead-zinc oxide ore is becoming increasingly important; while mining high-quality lead and zinc resources, a large number of low-grade lead-zinc oxide ores are due to taste and recovery. The disposal cost is too high and the storage in the mine cannot be used, which not only causes waste of resources, but also causes serious damage to the ecological environment of the mining area. How to use low-grade lead-zinc oxide ore economically and efficiently has always been a major problem faced by the lead-zinc industry.

At present, the methods for resource utilization of lead-zinc oxide ore mainly include beneficiation process, combination process of beneficiation and metallurgy, and high-temperature reduction and volatilization process. The beneficiation process mainly uses flotation agents to enrich the sulfide ore. For the sulfide ore beneficiation process, many domestic and foreign scholars have studied it, and I will not repeat it here. Flotation, the treatment process is more complicated, the cost is higher, and the yield is low. The combined process of beneficiation and smelting is to first perform acid leaching to recover oxidized ore, and then perform flotation to recover sulfide ore. The leaching residue, which is a hazardous waste, needs further harmless treatment. The waste acid and waste residue are difficult to deal with, and the treatment cost is high. The high-temperature reduction volatilization process refers to the high-temperature reduction and volatilization of lead-zinc oxide ore in high-temperature pyro-smelting devices such as smoke furnaces, rotary kilns, and tunnel kilns to generate zinc oxide dust and slag, and the slag produced is general solid waste. At present, when processing lead-zinc ore, the high-temperature reduction and volatilization process of rotary kiln is the mainstream process and has great advantages, but it has low heat utilization rate (about 10% heat utilization rate), high energy consumption, and low production capacity. Production costs remain high. To this end, the majority of technical workers and R&D personnel are also paying a lot of energy to reduce the energy consumption of high-temperature reduction processes. For example, patent CN111270085A sets up a vacuuming device to make the rotary kiln reduce and volatilize in a vacuum state, reduce the partial pressure of zinc vapor in the system through negative pressure, and reduce the temperature required for reduction and volatilization, thereby saving energy. The patent CN106766870A increases the heat utilization rate by adding a heat exchanger outside the reduction zone of the rotary kiln. These methods are helpful in improving the utilization rate of thermal energy of the rotary kiln, but the effect is limited, the thermal energy is still not fully utilized, and the problem of high energy consumption in the high-temperature reduction and volatilization process is still not solved. Existing smelting equipment has high energy consumption and high production cost, which is more and more unacceptable to enterprises. The high energy consumption and high cost of existing smelting equipment have become the main constraints to the resource utilization and harmless treatment of low-grade lead and zinc oxide. question.

SUMMARY OF THE INVENTION

Taking the existing high-temperature reduction and volatilization equipment for lead-zinc oxide ore with a processing capacity of 600t/d as an example, zinc oxide dust is produced by reduction and volatilization at 1300°C in a strong reducing atmosphere. The mass ratio of coal to mine is about 50%, and there are problems of small processing capacity and high production cost. In response to the above problems, the inventor has conducted a lot of experimental work and creative research, and has optimized and transformed the high-temperature reduction and volatilization equipment, set up a preheating unit and a precalciner, and made full use of the reduction and volatilization heat energy. The contact time between the material and the flue gas is controlled by the particle size of the ore. After the material is preheated and pre-decomposed, the heat utilization rate and the reduction and volatilization speed of the material are greatly improved. Through the technical scheme of the present invention, the thermal energy utilization rate is as high as 45-65%, and the fuel consumption is 40% of the existing technology. At the same time, due to the accelerated reduction and volatilization rate, the processing capacity of oxidized ore can reach 400t/h, which is more than 15 times that of the current production process.

Therefore, the present invention has two main purposes. The first purpose is to provide a system for the harmless treatment of lead-zinc oxide ore resources, and the second purpose is to provide a method for the harmless treatment of lead-zinc oxide ore resources.

The first object of the present invention is achieved through the following technical solutions:

The system and method for the harmless treatment of lead-zinc oxide ore resources include a preheating unit 1, a precalciner 2, a rotary kiln 3 and a cooler 4, and the lead-zinc oxide ore is added from the preheating unit 1; the preheating Unit 1 is provided with a discharge port and is connected to the precalciner 2; the top flue gas outlet of the precalciner 2 is connected to the preheating unit 1, and the precalciner 2 is provided with a pulverized coal feeding port, a pellet coal feeding port, a secondary At the tuyere, the bottom of the precalciner 2 communicates with the rotary kiln 3 .

Further, the described lead-zinc oxide ore resource harmless treatment system also includes a cooler 4; one end of the cooler 4 is connected to the kiln head of the rotary kiln 3, and the other end is a cold slag discharge port; The secondary hot air is communicated to the precalciner 2 through a pipeline; the kiln head of the rotary kiln 3 is provided with a hot air spray gun to provide combustion air.

Further, the preheating unit 1 is composed of a preheater connected by a pipeline; the lead-zinc oxide material is added from the feeding port of the preheating unit.

Further, the preheating unit 1 can be set to preheat the material in direct contact with the flue gas, or can be set up to preheat the material in indirect contact with the flue gas.

Further, the lead-zinc oxide ore can be fed continuously or intermittently.

Further, the temperature of the flue gas at the outlet of the preheating unit is less than or equal to 400°C.

The second object of the present invention is achieved through the following technical solutions:

Described a kind of lead-zinc oxide ore resource harmless treatment method, comprises the following steps:

A. The lead-zinc oxide ore is crushed, dried, ground and homogenized;

B. Add lead oxide ore into the preheating unit for preheating;

C. Under the oxidizing atmosphere, the preheated lead-zinc oxide is added to the pre-decomposition furnace to complete the pre-decomposition reaction, and impurities such as sulfur and chlorine are removed; the high-temperature flue gas produced by the pre-decomposition reaction is sent to the pre-decomposition furnace The thermal unit preheats the lead-zinc oxide ore;

D. The intermediate material produced by the precalciner enters the rotary kiln, and in a reducing atmosphere, the reduction and volatilization of lead and zinc in the lead-zinc oxide ore are completed;

E. The high-temperature slag waste heat generated by the reduction reaction is recovered for the pre-decomposition of step C and the combustion air of step D.

In one step, the high-temperature preheating described in step B means that in the preheating unit, the high-temperature flue gas directly exchanges heat with the lead-zinc oxide ore or the high-temperature flue gas indirectly preheats the lead-zinc oxide ore.

Further, under the oxidizing atmosphere described in step C, the pre-decomposition temperature is ≥900°C.

Further, under the reducing atmosphere described in step D, the reaction temperature is ≥1100°C.

Further, the lead-zinc oxide ore described in step A is one or more mixed ore in lead-zinc oxide ore, low-grade oxide lead-zinc ore or oxygen-sulfur mixed ore

Beneficial effects of the present invention:

In the present invention, a preheating unit is set, and the preheating unit is used to preheat the lead-zinc oxide ore, the lead-zinc oxide ore is preheated in the preheating unit, and the temperature of the lead-zinc oxide ore at the outlet of the preheating unit is greater than or equal to 600°C. The heat exchange between the smelting flue gas and the lead-zinc oxide ore in the preheating unit can not only effectively recover the waste heat in the flue gas, but also improve the temperature and reaction rate of the lead-zinc oxide ore entering the furnace, so as to improve the treatment system of the lead-zinc ore. production capacity and reduce energy consumption.

In the present invention, by setting a precalciner and controlling the precalciner to be an oxidizing atmosphere, the pulverized coal is completely burned in the precalciner, the temperature of the lead-zinc oxide ore is further increased, carbonates such as CaCO3 are heated and decomposed, and sulfides such as ZnS are heated and decomposed. Medium sulfur is removed by oxidation. The incompletely burned CO and other combustibles in the rotary kiln are completely burned here, and the fuel utilization rate is effectively improved; at the same time, the hot air of the rotary kiln is recycled into the precalciner through the cooler, and the heat energy is effectively recovered. The removal of impurities can be achieved using less fuel.

By using a cooler, the invention not only ensures that the residual carbon in the kiln slag is completely burned, but also can effectively recover the waste heat of the kiln slag, reduce the temperature of the kiln slag from 900°C-1100°C to ≤120°C, and produce high-temperature hot air for use as a rotary kiln And precalciner secondary air, the remaining hot air can be used for waste heat power generation or grinding and drying materials. Due to the use of the cooler, the utilization rate of waste heat in the kiln slag is more than 60%, which can effectively improve the heat utilization rate of the system and reduce the production cost.

The invention creatively uses devices such as preheating unit, precalciner and cooler, which not only realizes the recovery and utilization of flue gas and kiln slag waste heat, but also strengthens the metallurgical reaction process and accelerates the reduction and volatilization of materials in the furnace. Through the above measures, the processing capacity and heat utilization rate of the processing system have been greatly improved compared with the traditional production process. The daily processing capacity of lead-zinc oxide ore can reach more than 15 times that of the traditional production process; the heat utilization of the system can reach more than 50%, which is about 5 times that of the reduction and volatilization of the rotary kiln or the smoke furnace. Due to the significant increase in heat utilization rate and production capacity, the treatment cost of lead-zinc oxide ore is reduced to about 350 yuan/t, which is only 1/2 of the production cost of reduction volatilization in the existing rotary kiln or smoke furnace.

Description of drawings

Fig. 1 is the device structure schematic diagram of the present invention;

Fig. 2 is the structural schematic diagram of the system embodiment 2 of the present invention;

In the figure, 1-preheating unit, 2-precalciner, 3-rotary kiln, 4-cooler.

Detailed ways

In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate the understanding of the skilled person.

In the specific embodiment, unless otherwise specified, the percentages described are all percentages by mass.

The invention provides a harmless treatment system of lead-zinc oxide ore resources.

Example 1:

As shown in FIG. 1 , a system for the harmless treatment of lead-zinc oxide ore resources includes: a preheating unit 1 , a precalciner 2 , a rotary kiln 3 and a cooler 4 .

The preheating unit 1 is communicated with the precalciner 2. In the preheating unit 1, the lead-zinc oxide material is in indirect or direct contact with the zinc oxide flue gas from the precalciner 2 to complete the preheating of the lead-zinc oxide material. Unit 1 can use any gas-solid heat exchange equipment that can realize direct or indirect contact heat exchange between zinc oxide fume and lead and zinc oxide materials, such as: cyclone preheating unit, multi-heart furnace preheating unit and the inner layer is the material channel, the outer layer is the material channel. The layer is a casing type heat exchange equipment such as a flue gas channel, etc. In the preheating unit 1, the lead and zinc oxide materials are preheated, and the heat in the flue gas is recovered at the same time to improve the utilization rate of heat energy. The temperature of the flue gas coming out of the preheating unit 1 is less than or equal to 400°C.

The kiln head of the rotary kiln 3 is provided with a hot air spray gun to provide combustion air or heat energy into the rotary kiln 3 . The bottom of the precalciner 2 is communicated with the kiln tail of the rotary kiln 3 . One end of the cooler 4 is connected to the kiln head of the rotary kiln 3, and the other end is the discharge port for cold slag. The cooler 4 recovers the waste heat in the rotary kiln 3 and generates 600°C-900°C hot air, and sends it to the precalciner 2 and the rotary The inside of the kiln 3 is used as the secondary combustion air.

By setting the cooler 4, the waste heat of the high-temperature kiln slag produced by the rotary kiln 3 is recovered to obtain low-temperature slag and 600°C-900°C hot air, and the hot air is recovered and sent to the precalciner 2 or the rotary kiln 3 for recycling. By recovering the flue gas and slag waste heat of the rotary kiln 3, the consumption of pulverized coal in the precalciner 2 can be greatly saved, and at the same time, the pulverized coal in the precalciner and the incompletely burned CO in the rotary kiln are completely burned, and the precalciner 2 Temperature≥900℃. In the precalciner 2, carbonates such as CaCO3 are completely decomposed, and sulfur in sulfides such as ZnS is oxidized and removed.

The precalciner 2 is provided with a pulverized coal feeding port, a secondary tuyere and a granular coal feeding port, and the granular coal feeding port liquid can be set at the kiln tail of the rotary kiln. Add pulverized coal with particle size ≤80μm and moisture ≤1% from the pulverized coal feed port to supplement the heat for the precalciner 2; the secondary tuyere is used to provide oxygen, which plays the role of providing oxygen for pulverized coal combustion and oxidative desulfurization; 2mm≤grain size≤8mm, moisture≤10% pellet coal is added to the coal feeding port. The pelletized coal is added to the rotary kiln 3 through the precalciner 2 to provide heat for the rotary kiln, and more importantly, to provide a reducing atmosphere to reduce The purpose of volatilizing ZnO and PbO.

Control the amount of pulverized coal added in the precalciner 2 to be 0-15% of the amount of lead-zinc oxide ore, and control the excess air coefficient in the precalciner 2 to 1.2-1.5, so that the pulverized coal is burned more fully, and the oxidizing atmosphere in the furnace is ensured. In the precalciner 2, the pulverized coal and incompletely combusted CO in the rotary kiln are completely burned. The precalcining furnace 2 is arranged in a cylindrical shape, the furnace waist is contracted, and the inner lining is refractory bricks. The shrinkage of the furnace waist can speed up the flow rate of the flue gas at the waist, make the flow rate of the flue gas and mineral powder change abruptly, achieve the dispersion effect, make the contact between the lead-zinc oxide mineral powder and the pulverized coal and flue gas more fully, and prolong the fall of the lead-zinc oxide mineral powder. time to ensure that the material fully reacts in the furnace.

Control the amount of coal added in the precalciner 2 to be 6-15% of the lead-zinc oxide ore, and control the excess air coefficient of the rotary kiln 3 to be 0.8-1.2 to ensure a strong reducing atmosphere in the rotary kiln. ZnO and PbO are completely volatilized into the flue gas. The granular coal added from the precalciner 2 basically does not participate in the reaction in the precalciner 2, and enters the rotary kiln to burn and provide a reducing atmosphere to reduce and volatilize the lead-zinc oxide ore.

The temperature of the slag produced by the rotary kiln is as high as 900-1400°C. After cooling by the cooler 4, the temperature of the slag drops to 80-120°C, and the temperature of the secondary air produced by the cooler 4 is 600-900°C.

The lead-zinc oxide ore resource harmless treatment system can adopt continuous feeding or intermittent feeding. Intermittent feeding is adopted. When the content of zinc in the precalciner 2 reaches 15-35%, the feeding is stopped. The zinc-containing materials in the system continue to be reduced and volatilized to produce zinc oxide fume. The zinc oxide fume is recovered in the dust collection system. The resulting soot contains 45-60% zinc. After the zinc-containing fume and dust are recovered, continue feeding, and so on. Continuous feeding is adopted. When the zinc content of the material in precalciner 2 reaches 25-45%, the discharge port at the bottom of the precalciner is opened to discharge the zinc-containing material, and the zinc is recovered by fire or wet treatment. The unloading can be intermittent or continuous. Through intermittent unloading, materials with higher zinc content can be obtained.

Example 2:

A system for the harmless treatment of lead-zinc oxide ore resources, the preheating unit is a cyclone preheating unit, and the rest are the same as those in Embodiment 1. As shown in FIG. 2 , the processing system includes: a cyclone preheating unit 1 , a precalciner 2 , a rotary kiln 3 and a cooler 4 . The cyclone preheating unit 1 is composed of 5-stage cyclone dust collectors connected by pipelines (as shown in Figure 2, C1 represents the primary cyclone dust collector, C2 represents the secondary cyclone dust collector, and so on). The lead-zinc oxide ore is added from the connecting pipeline of the first-stage cyclone C1 and the second-stage cyclone C2 of the preheating unit. The waste heat is recovered, and the lead-zinc oxide ore is preheated to 600℃-900℃. The flue gas outlet of the top of the precalciner 2 is connected to the air inlet of the fifth stage cyclone C5 of the preheating unit, and the discharge port of the fourth stage cyclone C4 of the cyclone preheating unit 1 is connected to the middle of the precalciner 2, because the whole The cyclone separation system operates under negative pressure. If the C4 discharge port is connected to the upper part of the precalciner 2, a large amount of lead-zinc oxide ore will be taken away before the precalciner has fully reacted. The ore powder coming down from the C4 discharge port is fully reacted. The discharge port of the fifth-stage cyclone C5 is connected to the bottom of the precalciner 2 . The kiln head of the rotary kiln 3 is provided with a hot air spray gun to provide combustion air or heat energy into the rotary kiln 3 . The bottom of the precalciner 2 is communicated with the kiln tail of the rotary kiln 3 . The cooler 4 adopts a grate cooler. One end of the cooler 4 is connected to the kiln head of the rotary kiln 3, and the other end is the outlet for the cold slag. The grate cooler 4 recovers the waste heat in the rotary kiln 3 and produces hot air at 600°C-900°C. , and sent to the precalciner 2 and the rotary kiln 3 as secondary combustion air.

Cyclone preheating unit 1 consists of 5-stage cyclone dust collectors. The discharge port of the first-stage cyclone dust collector C1 is connected to the outlet flue of the third-stage cyclone dust collector C3 through a pipeline, and the second-stage cyclone dust collector C2 discharges The material port is connected to the outlet flue of the fourth and fourth-stage cyclone dust collector C4 through a pipeline. The above structure can ensure that the material is in full contact with the flue gas, and prolong the preheating time to achieve the purpose of improving the heat utilization rate. The flue gas processed by the cyclone preheating unit 1 is discharged through the outlet of the first-stage cyclone, and the temperature of the flue gas at the outlet is less than or equal to 400°C.

The invention also provides a method for the harmless treatment of lead-zinc oxide ore resources.

Example 1: (direct contact heat exchange)

A method for the harmless treatment of lead and zinc oxide resources, the specific steps are as follows:

(1) The composition of 100000t is Pb 1.26%; Zn 6.73%; CaO 27.86%; SiO ₂ 22.34%; Al ₂ O ₃ 2.35%; MgO 1.57%; The grade lead-zinc oxide ore is crushed and ball-milled in sequence. After crushing, the particle size is less than or equal to 35mm, accounting for 80%; for ball milling, the particle size is less than or equal to 80μm and the moisture content is less than or equal to 0.5%.

(2) Divide 24000t of anthracite with carbon content of 65%, 2mm≤grain size≤8mm and moisture≤10% into two parts, of which 12000t is ball milled, the particle size of pulverized coal is≤80μm, moisture≤1%; the other 12000t is prepared with 2mm≤particle size ≤8mm, the granular coal with moisture ≤10% is stored for use.

(3) Using a production system with a processing capacity of 5000t/d, the ball-milled lead-zinc oxide ore is evenly fed into the preheating unit according to the material amount of 250t/h, and the outlet flue gas temperature of the preheating unit is controlled to be 310℃, and the outlet pressure is -5800Pa , the working condition wind speed is 12m/s. The lead-zinc oxide ore is preheated to 860°C.

(4) The pulverized coal with particle size ≤80μm and moisture ≤1% is uniformly sprayed into the precalciner at a speed of 18.4t/h, and the excess air coefficient is controlled to 1.25. The furnace is in an oxidizing atmosphere and the temperature in the furnace is 1150℃. The pulverized coal in the precalciner and the remaining CO produced in the rotary kiln are fully burned; the sulfur, arsenic, fluorine, chlorine and other impurities contained in the lead-zinc oxide ore entering the precalciner from the preheater are removed, and CaCO ₃ Wait for the carbonate to decompose. The tail gas is sent to desulfurization after dust collection.

(5) The granular coal with carbon content of 65%, 2mm≤grain size≤8mm, and moisture≤10% is uniformly added to the precalciner at a speed of 15t/h, and the excess air coefficient of the rotary kiln is controlled to 0.85, and the rotary kiln is strongly reduced. Atmosphere, the temperature in the kiln is 1350℃.

(6) After 5 hours of continuous feeding, the zinc-containing lead-zinc ore in the preheater is enriched to 35%, and the discharge port at the bottom of the precalciner is opened to discharge the high-zinc-containing materials, and the zinc is recovered by fire or wet treatment. Metal. The method can be continuous feeding, intermittent or continuous discharge.

(7) Send the 1240°C kiln slag produced by the rotary kiln to the cooler to recover the waste heat, and produce 85°C kiln slag and 950°C hot air. The thermal efficiency of the cooler is greater than or equal to 65%. The hot air produced is sent to the kiln head of the rotary kiln and the precalciner as the secondary combustion air, the remaining hot air is used as the heat source for the preparation of pulverized coal and the drying of lead-zinc ore, and the rest goes into the waste heat boiler for low-temperature power generation.

Example 2: (Indirect Contact Heat Exchange)

A method for the harmless treatment of lead-zinc oxide ore resources, the specific steps are as follows:

(1) The composition of 1 million t is Pb 5.26%; Zn 13.73%; CaO 17.09%; SiO ₂ 35.94%; Al ₂ O ₃ 0.85%; MgO 3.57%; The low-grade lead-zinc oxide ore is crushed and ball-milled in turn. After crushing, the particle size is less than or equal to 18mm, accounting for 75%; for ball milling, the particle size is less than or equal to 75μm and the moisture content is less than or equal to 0.9%.

(2) Divide 200,000 tons of anthracite with carbon content of 58%, 2mm≤grain size≤8mm, and moisture≤10% into two parts, of which 80,000 tons are ball-milled, the particle size of pulverized coal is≤80μm, and the moisture≤1%; the other 12 10,000 tons of coal is prepared as 2mm≤granularity≤8mm, and the moisture content≤10% of the granular coal is stockpiled for future use.

(3) Using a production system with a processing capacity of 10000t/d, the ball-milled lead-zinc oxide ore is evenly fed into the preheater according to the material amount of 500t/h, and the flue gas temperature at the outlet of the preheater is controlled to 385℃, and the outlet pressure is -7000Pa , the working condition wind speed is 12m/s. Preheat the lead oxide ore to 715°C.

(4) The pulverized coal with particle size ≤80μm and moisture ≤1% is uniformly sprayed into the precalciner at a speed of 32.5t/h, and the excess air coefficient is controlled to 1.45. The precalciner is in an oxidizing atmosphere and the temperature is 1080℃. The pulverized coal in the precalciner and the unburned CO in the rotary kiln are fully burned; the sulfur, arsenic, fluorine, chlorine and other impurities contained in the lead-zinc oxide ore entering the precalciner from the cyclone preheater are removed, and the CaCO ₃ etc. carbonates are decomposed. The tail gas is sent to desulfurization after dust collection.

(5) The granular coal with carbon content of 58%, 2mm≤grain size≤8mm, and moisture≤10% is uniformly added to the precalciner at a speed of 62.5t/h, and the excess air coefficient of the rotary kiln is controlled to 0.95, and the rotary kiln is strong. Reducing atmosphere, the temperature in the kiln is 1350℃.

(6) The zinc oxide flue gas produced by the reduction and volatilization of the rotary kiln passes through the precalciner and enters the outer flue gas pipeline of the preheating unit for dust collection treatment. After dust collection, zinc oxide dust is obtained. The zinc oxide dust contains 55% zinc. The production process Continuous feeding in the middle, continuous production of zinc oxide fume. The heat exchange effect of the preheating unit of this method is worse than that of the direct contact heat exchange, but the production process is continuous and relatively stable. It is suitable for processing materials with zinc content ≥ 10%.

(7) Send the 1160°C kiln slag produced by the rotary kiln to the cooler to recover waste heat, and produce 115°C kiln slag and 1040°C hot air. The thermal efficiency of the cooler is greater than or equal to 58%. The hot air produced is sent to the kiln head of the rotary kiln and the precalciner as the secondary combustion air, the remaining hot air is used as the heat source for the preparation of pulverized coal and the drying of lead-zinc ore, and the rest goes into the waste heat boiler for low-temperature power generation.

Example 3: (Cyclone preheating unit preheating)

A method for the harmless treatment of lead-zinc oxide ore resources, the specific steps are as follows:

(1) The raw material composition of 50000t is Pb 2.26% Zn 9.73% CaO 21.86% SiO ₂ 28.34% Al ₂ O ₃ 0.35% MgO 0.57% S 4.34% (the oxidation rate of lead and zinc reaches 60%) low-grade lead-zinc oxide ore Crushing and ball milling are carried out in sequence. After crushing, the particle size is less than or equal to 25mm, accounting for 70%; the material is ball-milled to a particle size of less than or equal to 60μm, and the moisture content is less than or equal to 0.8%.

(2) Divide 10,000t of anthracite with carbon content of 60%, 2mm≤particle size≤6mm, and moisture≤8% into two parts, of which 5000t is ball-milled, the particle size of pulverized coal is≤60μm, and the moisture≤0.6%; the other 5000t is prepared as 2mm≤ Granular coal with particle size ≤ 8mm and moisture ≤ 10% is stored for use.

(3) Using a production system with a processing capacity of 3000t/d, the ball-milled lead-zinc oxide ore is uniformly fed into the cyclone preheater according to the material amount of 136t/h, and the flue gas temperature at the outlet of the cyclone preheater is controlled to be 290°C and the outlet pressure -6000Pa, working condition wind speed 8m/s. The lead-zinc oxide ore is preheated to 960°C.

(4) The pulverized coal with particle size ≤60μm and moisture ≤0.6% is uniformly sprayed into the precalciner at a speed of 10.9t/h, and the excess air coefficient is controlled to 1.15. The precalciner is in an oxidizing atmosphere and the temperature is 1050℃. The pulverized coal in the precalciner and the unburned CO in the rotary kiln are fully burned; the sulfur, arsenic, fluorine, chlorine and other impurities contained in the lead-zinc oxide ore entering the precalciner from the cyclone preheater are removed, and the CaCO ₃ etc. carbonates are decomposed. The tail gas is sent to desulfurization after dust collection.

(5) The granular coal with carbon content of 60%, 2mm≤grain size≤6mm, and moisture≤8% is uniformly added to the precalciner at a speed of 12t/h, and the excess air coefficient of the rotary kiln is controlled to 0.75, and the rotary kiln is strongly reduced. Atmosphere, the temperature in the kiln is 1310℃.

(6) After 5 hours of continuous feeding, the zinc-containing lead-zinc ore in the preheater is enriched to 32%, and the feeding is stopped. The zinc-containing material in the preheater is further reduced and volatilized to produce zinc oxide dust and enter the dust collection system. This method adopts batch feeding production, feeding from the flue gas pipeline of the preheating unit, continuing to feed continuously for 5 hours, stopping feeding for 1 hour to carry out volatilization reaction, until the zinc content of lead-zinc oxide ore in the preheater is enriched to 32%, and continue to continue continuous feeding. Feeding for 5h, such a cycle, enrichment and recovery to obtain high-grade zinc oxide fume, the fume contains 55% zinc.

(7) The 1180°C kiln slag produced by the rotary kiln is sent to a grate cooler to recover waste heat, and the kiln slag with a temperature of 95°C and a hot air of 1000°C are produced. The thermal efficiency of the grate cooler is ≥62%. The hot air produced is sent to the kiln head of the rotary kiln and the precalciner as the secondary combustion air, the remaining hot air is used as the heat source for the preparation of pulverized coal and the drying of lead-zinc ore, and the rest goes into the waste heat boiler for low-temperature power generation.

Above, by adopting the method of Example 1, the obtained material contains low zinc, the production process is stable and continuous, and the heat exchange effect is good. Using the method of Example 2, the process is continuous and stable, but the heat exchange effect is poor. Adopt the mode of embodiment 3, the obtained smoke dust contains the highest zinc, and the heat exchange effect is the best, but the production process is intermittent feeding, and the process is discontinuous;

Comparative ratio:

Using the rotary kiln with the same processing capacity as Example 3, the raw material composition of 1000t is Pb 2.26%; Zn 9.73%; CaO 21.86%; SiO ₂ 28.34%; Al ₂ O ₃ 0.35%; MgO 0.57%; S 4.34% (lead , low-grade lead-zinc oxide ore with zinc oxidation rate of 60%) is crushed and ball-milled in turn. After crushing, the particle size is less than or equal to 25mm, accounting for 70%; the material is ball-milled to a particle size of less than or equal to 60μm, and the moisture content is less than or equal to 0.8%.

The crushed lead-zinc oxide ore and anthracite are added into the rotary kiln at the ratio of 1:0.45, and the temperature of the rotary kiln is controlled to 1300℃ and the air coefficient is 0.75. The material is preheated and heated up in the rotary kiln, and volatilized to produce high-temperature kiln slag and flue gas. The kiln slag is quenched by water for take-out; the flue gas is cooled by the surface cooler, and the dust of the zinc oxide is recovered after the dust is collected by the cloth bag. Using this method, the kiln slag and flue gas waste heat are not recycled, the coal consumption is as high as 40%-55%, and the heat utilization rate is about 10%. The zinc content in the zinc oxide dust is 55%.

Through the comparative example, compared with the conventional reduction volatilization system with only rotary kiln, the technical solution of the present application reduces the coal consumption per ore by 55.5% and increases the production capacity by 15.63 times.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should Various changes may be made in details without departing from the scope of the invention as defined by the claims.

Claims (10)

1. A harmless treatment system for the recycling of lead-zinc oxide ore, characterized in that: the harmless treatment system for recycling lead-zinc oxide ore comprises a preheating unit (1), a precalciner (2), a rotary The kiln (3), the lead-zinc oxide ore is added from the preheating unit (1); the preheating unit (1) is provided with a discharge port and is connected to the precalciner (2); the top flue gas of the precalciner (2) is The outlet is connected to the preheating unit (1), the precalciner (2) is provided with a pulverized coal feed inlet and a secondary air outlet, and the bottom of the precalciner (2) is communicated with the rotary kiln (3). 2 . The harmless treatment system for recycling lead-zinc oxide ore according to claim 1, characterized in that: the system for recycling harmless lead-zinc oxide ore further comprises a cooler (4); One end of the cooler (4) is connected to the kiln head of the rotary kiln (3), and the other end is the discharge port for cold slag; the secondary hot air generated by the heat exchange of the cooler (4) is connected to the precalciner (2) through a pipeline; The kiln head of the rotary kiln (3) is provided with a hot air spray gun to provide combustion air. 3 . The harmless treatment system for reclaiming lead-zinc oxide ore according to claim 1 or 2, characterized in that: in the preheating unit (1), the lead-zinc oxide ore is directly contacted with the flue gas to preheat or Indirect contact preheating. 4 . The harmless treatment system for resourcing lead-zinc oxide ore according to claim 3 , wherein the lead-zinc oxide ore can be fed continuously or intermittently. 5 . 5 . The harmless treatment system for recycling lead-zinc oxide ore according to claim 4 , wherein the temperature of the flue gas at the outlet of the preheating unit ( 1 ) is less than or equal to 400° C. 6 . 6. A method for the harmless treatment of lead-zinc oxide ore resources, characterized in that: the described method for the harmless treatment of lead-zinc oxide ore resources comprises the following steps: A. The lead-zinc oxide ore is crushed, dried, ground and homogenized; B. Add lead oxide ore into the preheating unit for preheating; C. In an oxidizing atmosphere, add the preheated lead and zinc oxide into the precalciner to complete the predecomposition reaction, and remove impurities such as sulfur and chlorine; the high temperature flue gas produced by the predecomposition reaction is sent to step (2) The preheating unit preheats lead oxide zinc ore; D. The intermediate material produced by the precalciner enters the rotary kiln, and in a reducing atmosphere, the reduction and volatilization of lead and zinc in the lead-zinc oxide ore are completed; E. The high-temperature slag waste heat generated by the reduction reaction is recovered for the pre-decomposition of step C and the combustion air of step D. 7. A method for treating lead-zinc oxide ore as a resource and harmless treatment according to claim 5, characterized in that: the preheating described in step B means that in the preheating unit, the lead-zinc oxide ore and high temperature flue gas are treated Direct or indirect contact to preheat lead-zinc oxide ore. 8 . The method for the harmless treatment of lead-zinc oxide ore according to claim 6 , wherein: in the oxidizing atmosphere described in step C, the pre-decomposition temperature is ≥900° C. 9 . 9 . The method for the harmless treatment of lead-zinc oxide ore resources according to claim 6 , wherein in the reducing atmosphere described in step D, the reaction temperature is greater than or equal to 1100° C. 10 . 10. a kind of lead-zinc oxide ore resource harmless treatment method according to claim 6, is characterized in that: the lead-zinc oxide ore described in step A is lead-zinc oxide ore, low-grade lead-zinc oxide ore or oxygen One or more mixed ore of sulfur mixed ore.

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