A method for reducing energy consumption of a zinc hydrometallurgy residue treatment process

Abstract

The present application relates to a kind of methods for reducing the energy consumption of zinc hydrometallurgy slag treatment process, which comprises the following steps: (1) mixing zinc hydrometallurgy slag, coal powder, sodium bicarbonate and water to obtain a mixture; (2) ball milling and granulating the mixture to obtain granular material; (3) countercurrent drying the granular material to obtain dry material and low-temperature flue gas; (4) adding the dry material into a side-blown smelting furnace for smelting to obtain zinc oxide dust I, flue gas at 1080-1120°C and smelting slag; the flue gas at 1080-1120°C is cooled and dusted after entering a waste heat boiler to obtain zinc oxide dust II and flue gas at 300-340°C, which is introduced into an acid-making process; (5) adding the smelting slag into a fuming furnace, adding coal powder for reaction to obtain discard, flue gas at 1100-1200°C and zinc oxide dust III; the flue gas at 1100-1200°C is cooled and dusted after entering a waste heat boiler to obtain zinc oxide dust IV and flue gas at 300-340°C, which is introduced into an acid-making process. The present application has high recovery rate and low energy consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste residue treatment, and particularly relates to a method for reducing energy consumption of a wet zinc smelting residue treatment process. BACKGROUND

[0002] Currently, the wet zinc smelting residue treatment widely adopts a melting+fuming process, and the main energy consumption is the endothermic melting of the residue, so the key of the process lies in the melting of the residue, that is, the side-blown melting furnace melting. Since there is no heat-generating element in the wet zinc smelting residue, the melting mainly relies on external heating. If oxygen enrichment is not used, the coal rate is 40% or even higher. The side-blown melting furnace adopts a dispersed coal adding mode, in which a small part of the coal is added into the furnace charge in the form of granular coal and is dispersed in the molten pool to burn and participate in the reduction reaction, and most of the coal is directly sprayed into the molten pool in the form of coal powder through the side-blown lance. The side-blown lance uses oxygen-enriched combustion-supporting air, and the oxygen-enriched air concentration sprayed into the furnace is >50%. The lance is of a multi-channel structure, which is different from the existing fuming furnace lance, and has a fast combustion speed and a high flame temperature. Such submerged combustion directly contacts the melt, and the high-speed gas sprayed into the molten pool improves the molten pool stirring intensity and accelerates the heat and mass transfer process in the molten pool, so that the effect of rapidly melting the furnace charge can be achieved. At the same time, the use of oxygen-enriched air for combustion-supporting reduces the flue gas volume and improves the thermal efficiency of the side-blown melting furnace, so that the fuel rate can be significantly reduced.

[0003] The residue material into the furnace and the granular coal are transferred from the residue batching bin to the mobile belt through the belt conveyor, and are uniformly added into the side-blown melting furnace through the belt conveyor. The melting furnace has a specification of 13m 2 The added granular coal and the sprayed coal powder supplement heat, the temperature in the furnace is controlled to be about 1200 DEG C, and a weak reducing atmosphere in the furnace is controlled to make the coal fully burn and improve the fuel heat utilization rate. The residue material into the furnace is melted and decomposed in the high-temperature environment, sulfur enters the flue gas, a small amount of zinc, lead and lead compounds volatilize into the flue gas, and Fe, SiO2, CaO and other impurities form slag. With the addition of the material, the thickness of the slag layer in the furnace continuously increases. When the molten slag in the furnace reaches a certain thickness, it is self-flowed into the fuming furnace through the flow channel for fuming. The side-blown melting furnace discharges the slag once every about 2h.

[0004] The fuming furnace is operated in cycles, one furnace every 2h. The fuming furnace only sprays coal powder and air, the air excess coefficient is controlled to be 0.6-0.7, a relatively strong reducing atmosphere in the furnace is maintained, the temperature in the furnace is controlled to be about 1250 DEG C, and the reduction and volatilization of lead and zinc are fully ensured. The final control of the discarded slag is that the zinc content is <2% and the lead content is 0.2%. The discarded slag is water-crushed and sold.

[0005] The dust-containing flue gas produced by the side-blown melting furnace is sent to the acid-making system after waste heat recovery through the waste heat boiler and electric dust collector; the dust-containing flue gas produced by the fuming furnace is sent to the desulfurization system after waste heat recovery through the waste heat boiler and bag dust collector; and the collected flue dust is the product zinc oxide of the project, which is packaged or loaded into a vehicle for sale.

[0006] In summary, in actual production, the treatment of zinc hydrometallurgy residue generally adopts the melting + fuming process, but the process is not ideal in energy saving and carbon reduction and valuable metal recovery effect, and has the following shortcomings: (1) low fuel utilization rate, high energy consumption in smelting and fuming process; (2) low zinc recovery rate; (3) high production cost, poor economic benefit. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a method for reducing the energy consumption of the zinc hydrometallurgy treatment process with high recovery rate and low energy consumption.

[0008] To solve the above problems, the method for reducing the energy consumption of the zinc hydrometallurgy residue treatment process comprises the following steps:

[0009] (1) mixing zinc hydrometallurgy residue, coal powder, sodium bicarbonate and water to obtain a mixture with a water content of 35-45%; the addition amount of coal powder is 10% of the mass of zinc hydrometallurgy residue; the addition amount of sodium bicarbonate is 2% of the mass of zinc hydrometallurgy residue;

[0010] (2) placing the mixture in a wet ball mill for uniform mixing, and then conveying it to a granulator after ball milling for 30 min, and adding a binder for granulation to obtain a granular material with a particle size of 20-25 mm;

[0011] (3) uniformly adding the granular material into a rotary drum dryer, and at the same time, inputting hot flue gas at 750-850 DEG C into the rotary drum dryer to dry in a countercurrent drying manner, and obtaining dry material with a water content of ≤14% and low-temperature flue gas with a temperature of 130-160 DEG C; the low-temperature flue gas directly enters a dust collection system;

[0012] (4) adding the dry material into a side-blown smelting furnace, and at the same time, spraying oxygen-enriched air with a volume concentration of 70% for smelting, and controlling the temperature in the furnace at 1150 DEG C, and obtaining zinc oxide dust I, flue gas with a temperature of 1080-1120 DEG C and smelting slag after smelting; the flue gas with a temperature of 1080-1120 DEG C is cooled and dusted after entering a waste heat boiler to obtain zinc oxide dust II and flue gas with a temperature of 300-340 DEG C, and the flue gas with a temperature of 300-340 DEG C enters an acid making process;

[0013] ⑸The smelting slag is added into a fuming furnace, 8-10% of coal powder in mass is added, the air excess coefficient is kept at 0.5, the reaction is carried out in a strong reducing atmosphere for 1.5 hours, the furnace temperature is controlled at 1200-1250 DEG C; after the reaction, the abandoned slag containing zinc <1% and lead <0.15% is obtained, the flue gas with a temperature of 1100-1200 DEG C and zinc oxide dust III are obtained, the flue gas with a temperature of 1100-1200 DEG C is cooled in a waste heat boiler and then dust is collected, zinc oxide dust IV and flue gas with a temperature of 300-340 DEG C are obtained, and the flue gas with a temperature of 300-340 DEG C is introduced into an acid making process.

[0014] The water content of the wet zinc refining slag in the step 1 is 30-35%, the zinc content is 5.5-8.0%, and the lead content is 6.0-9.0%.

[0015] The binder in the step 2 is polyacrylamide with a mass concentration of 3-5 ‰, and the addition amount is 4-5% of the mass of the mixture.

[0016] Compared with the prior art, the method has the following advantages:

[0017] 1. The method provides a different raw material treatment method, solves the instability of the feeding material, adds a certain proportion of coal powder, solvent and bulking agent, and binder in the wet zinc refining slag granulation stage, improves the strength and air permeability of the feeding material, and strengthens the reduction performance of the smelting process, thereby improving the volatilization of zinc and lead in the smelting process, and the comprehensive volatilization rate of zinc and lead in the process is increased from about 80% of the prior art to more than 90%.

[0018] 2. The method directly adds coal powder in the batching and granulation process, and uniformly mixes by ball milling, which better improves the efficiency of the material combustion process, speeds up the heat transfer process, improves the fuel utilization rate, greatly reduces the coal powder consumption, and the coal powder rate in the smelting process is reduced from 20% of the prior art to 10%, and the economic benefit is remarkable.

[0019] 3. After the method is used, the zinc and lead contents of the abandoned slag material are reduced from 2% and 0.2% of the prior art to less than 1% and 0.15%, and the metal recovery rate is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 The flowchart of the application. DETAILED DESCRIPTION

[0022] As Figure 1 shown, a method for reducing the energy consumption of a wet zinc refining slag treatment process comprises the following steps:

[0023] (1) Mix wet zinc smelting slag, coal powder, sodium bicarbonate (a leavening agent), and water to obtain a mixture with a water content of 35-45%; the amount of coal powder added is 10% of the mass of wet zinc smelting slag; the amount of sodium bicarbonate added is 2% of the mass of wet zinc smelting slag.

[0024] The wet zinc slag contains 30-35% water, 5.5-8.0% zinc, and 6.0-9.0% lead.

[0025] (2) The mixture is placed in a wet ball mill and mixed evenly. After ball milling for 30 minutes, it is conveyed to a granulator for granulation. At the same time, a binder is added to ensure the strength of the granules, thus obtaining granules with 85% particle size of 20~25 mm. The proportion of fine powder should be minimized.

[0026] The adhesive is polyacrylamide with a mass concentration of 3-5‰, and its addition amount is 4-5% of the mass of the mixture.

[0027] (3) The granular material is uniformly added into the rotary dryer. Simultaneously, hot flue gas at 750~850℃ is introduced into the rotary dryer, employing a counter-current drying method. The flue gas and material flow in opposite directions and exchange heat fully to achieve the purpose of drying the material. After drying, dried material with a moisture content ≤14% and low-temperature flue gas at a temperature of 130~160℃ are obtained; the low-temperature flue gas directly enters the dust collection system.

[0028] (4) The dried material is added into the side-blown smelting furnace, and oxygen-enriched air with a volume concentration of 70% is injected for smelting. A small amount of natural gas is used for furnace heating. By increasing the oxygen concentration, the amount of flue gas can be significantly reduced, thereby reducing the energy consumption for subsequent flue gas treatment. The furnace temperature is controlled at 1150℃. The slag material melts and decomposes at high temperature. Sulfur enters the flue gas, and about 70% of zinc and lead volatilizes into the flue gas. Iron, silicon dioxide and other impurities are used for slag formation.

[0029] After smelting, zinc oxide dust I, flue gas at a temperature of 1080~1120℃ and smelting slag are obtained respectively. The flue gas at a temperature of 1080~1120℃ enters the waste heat boiler for cooling and dust collection, and zinc oxide dust II and flue gas at a temperature of 300~340℃ are obtained respectively. The flue gas at a temperature of 300~340℃ enters the acid production process.

[0030] (5) The smelting slag is added to the fuming furnace, along with 8% to 10% of its mass of pulverized coal. The excess air coefficient is maintained at 0.5 during this process. The reaction is carried out in a strong reducing atmosphere for 1.5 hours to ensure that zinc and lead are fully reduced. The furnace temperature is controlled at 1200 to 1250℃. After the reaction, waste slag containing less than 1% zinc and less than 0.15% lead, flue gas at 1100 to 1200℃, and zinc oxide dust III are obtained. The flue gas at 1100 to 1200℃ is cooled in a waste heat boiler and then collected for dust collection, resulting in zinc oxide dust IV and flue gas at 300 to 340℃. The flue gas at 300 to 340℃ is then introduced into the acid production process.

[0031] Example A method for reducing energy consumption in a hydrometallurgical zinc slag treatment process includes the following steps:

[0032] (1) Mix 100 kg of wet zinc smelting slag, 10 kg of coal powder, 2 kg of sodium bicarbonate (a leavening agent) with water to obtain 115 kg of mixture with a moisture content of 40%.

[0033] The wet zinc slag contains 35% water, 5.5-8.0% zinc, and 6.0-9.0% lead.

[0034] (2) The mixture is placed in a wet ball mill and mixed evenly. After ball milling for 30 minutes, it is conveyed to a granulator. At the same time, 5 kg of polyacrylamide with a mass concentration of 3-5‰ is added for granulation, resulting in 120 kg of granules with 85% of the particles having a size of 20-25 mm.

[0035] (3) The granular material is evenly added into the rotary drum dryer. At the same time, hot flue gas at 750~850℃ is input into the rotary drum dryer and dried by countercurrent drying method to obtain 82kg of dried material with a moisture content of ≤14% and low temperature flue gas at 130~160℃ respectively. The low temperature flue gas directly enters the dust collection system.

[0036] (4) The dried material is added into the side-blown smelting furnace, and oxygen-enriched air with a volume concentration of 70% is injected for smelting. The furnace temperature is controlled at 1150℃. After smelting, zinc oxide dust I, flue gas at a temperature of 1080~1120℃ and 80kg of smelting slag are obtained respectively. The flue gas at a temperature of 1080~1120℃ enters the waste heat boiler for cooling and dust collection, and zinc oxide dust II and flue gas at a temperature of 300~340℃ are obtained respectively. The flue gas at a temperature of 300~340℃ enters the acid production process.

[0037] (5) The smelting slag is added to the fuming furnace, along with 8 kg of pulverized coal. The excess air coefficient is maintained at 0.5 during this process. The reaction is carried out in a strong reducing atmosphere for 1.5 hours, with the furnace temperature controlled at 1200~1250℃. After the reaction, 53.6 kg of waste slag containing <1% zinc and <0.15% lead, flue gas at 1100~1200℃, and zinc oxide dust III are obtained. The flue gas at 1100~1200℃ is cooled in a waste heat boiler and then collected for dust collection, yielding zinc oxide dust IV and flue gas at 300~340℃. The flue gas at 300~340℃ is then introduced into the acid production process.

Claims

1. A method for reducing energy consumption of a zinc hydrometallurgy residue treatment process, comprising the following steps: 1) mixing zinc hydrometallurgy residue, coal powder, sodium bicarbonate and water to obtain a mixture with a water content of 35-45%; the addition amount of the coal powder is 10% of the mass of the zinc hydrometallurgy residue; the addition amount of the sodium bicarbonate is 2% of the mass of the zinc hydrometallurgy residue; the water content of the zinc hydrometallurgy residue is 30-35%, the zinc content is 5.5-8.0%, and the lead content is 6.0-9.0%; 2) placing the mixture in a wet ball mill for uniform mixing, conveying the mixture to a granulator after ball milling for 30 min, and adding a binder to perform granulation, thereby obtaining granular material with a particle size of 20-25 mm; 3) uniformly adding the granular material into a rotary drum dryer, inputting hot flue gas at 750-850 ℃ into the rotary drum dryer, and performing drying in a countercurrent drying manner, thereby obtaining dry material with a water content of ≤14% and low-temperature flue gas with a temperature of 130-160 ℃; the low-temperature flue gas directly enters a dust collection system; 4) adding the dry material into a side-blown smelting furnace, spraying oxygen-enriched air with a volume concentration of 70% into the furnace, and controlling the temperature in the furnace at 1150 ℃, thereby obtaining zinc oxide dust I, flue gas with a temperature of 1080-1120 ℃, and smelting residue; the flue gas with a temperature of 1080-1120 ℃ is cooled and dusted after entering a waste heat boiler, thereby obtaining zinc oxide dust II and flue gas with a temperature of 300-340 ℃; the flue gas with a temperature of 300-340 ℃ enters an acid production process; 5) adding the smelting residue into a fuming furnace, adding coal powder with a mass of 8-10% into the fuming furnace, maintaining an air excess coefficient of 0.5 during the process, reacting in a strong reducing atmosphere for 1.5 h, and controlling the temperature of the furnace at 1200-1250 ℃; after the reaction, obtaining abandoned residue with zinc content <1% and lead content <0.15%, flue gas with a temperature of 1100-1200 ℃, and zinc oxide dust III; the flue gas with a temperature of 1100-1200 ℃ is cooled and dusted after entering a waste heat boiler, thereby obtaining zinc oxide dust IV and flue gas with a temperature of 300-340 ℃; the flue gas with a temperature of 300-340 ℃ enters an acid production process.

2. A method of reducing energy consumption in a zinc hydrometallurgy residue treatment process according to claim 1, characterized in that: In step 2), the binder is polyacrylamide with a mass concentration of 3-5 ‰, and the addition amount of the binder is 4-5% of the mass of the mixture.

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