Method for treating smelting flue gas desulfurization gypsum solid waste at low cost by using copper flash converting furnace

Abstract

The invention discloses a method for low-cost treatment of smelting flue gas desulfurization gypsum solid waste by using a copper flash converting furnace, which comprises the steps of pretreatment and converting, and specifically comprises the following steps: crushing desulfurization gypsum to obtain a material a; copper matte is finely ground to obtain a material b; and after the material a and the material b are evenly mixed, matte flash blowing is conducted under the oxygen-enriched condition, and crude copper and slag are obtained. According to the method, the desulfurized gypsum solid waste is used for replacing a calcium oxide flux in the existing technological process, the characteristic that the desulfurized gypsum is decomposed into calcium oxide, SO2 and O2 flue gas through oxidation reaction heat in the pyrogenic blowing process is fully utilized, the flue gas acid making cost can be reduced through the by-product SO2, the smelting process is strengthened through O2, and the smelting efficiency is improved. And low-cost treatment and efficient resource utilization of the desulfurized gypsum solid waste are realized, and the original process or equipment does not need to be changed.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for treating gypsum solid waste from smelting flue gas desulfurization at low cost by using a copper flash converting furnace. Background Art

[0002] Nonferrous metal minerals mostly exist in the form of sulfides. During the smelting process of nonferrous metals such as copper, nickel, lead, zinc, molybdenum, tin, antimony, and cobalt, a large amount of SO 2 Flue gas, of which medium and high concentrations of SO 2 Flue gas is recycled to make sulfuric acid. In recent years, my country's nonferrous smelting industry has developed rapidly, and the production capacity and output of nonferrous metals have increased rapidly. Sulfuric acid made from smelting flue gas has become a stable growth variety in the sulfuric acid industry and is the main source of commercial acid. According to data, in 2022, my country's output of sulfuric acid made from smelting flue gas was 42.56 million tons, accounting for 39.78% of sulfuric acid production.

[0003] In the past, low-concentration flue gas was directly discharged after dust collection, and high-concentration flue gas was discharged after acid production. In recent years, the country has attached more and more importance to pollution control in the non-ferrous smelting industry and has issued a series of policies and regulations. The environmental protection standards for acid production are becoming more and more stringent. Even if the advanced two-transformation and two-absorption process is used, it is difficult for the tail gas of acid production to reach 400mg / m for a long time. 3 Therefore, flue gas desulfurization becomes the only available technology.

[0004] The dry / wet desulfurization technology currently used is applied in nonferrous smelting and acid production industries, such as sodium alkali method, lime / limestone-gypsum method (carbide slag-gypsum method), double alkali method, metal oxide desulfurization technology (zinc oxide method, magnesium oxide method, manganese oxide method), wet ammonia method, organic solvent circulation absorption method, activated coke adsorption method, hydrogen peroxide method, new catalytic method, etc. Among them, the lime / limestone-gypsum method is the most mature desulfurization technology at home and abroad, and it is also widely used by smelters. This process uses limestone as a desulfurizer, and after emulsification and pulping, it generates calcium hydroxide emulsion, which reacts with SO in the flue gas in the desulfurization tower. 2 Calcium sulfite is generated, and the calcium sulfite solution is oxidized by aeration to generate calcium sulfate. The specific reaction is as follows: CaO+H 2 O=Ca(OH) 2 Ca(OH) 2 +SO 2 =CaSO 3 +H 2 O 2CaSO 3 +O 2 =2CaSO 4 The lime / limestone-gypsum process is mature and reliable, with high desulfurization efficiency (primary desulfurization efficiency of more than 90%), and the source of desulfurization agent is abundant and cheap. The disadvantage is that the by-product desulfurization gypsum is of poor quality and difficult to dispose of, and can only be landfilled. Desulfurization gypsum is an industrial solid waste, facing the dual pressure of land occupation and environmental protection. Although there are ways to utilize desulfurization gypsum, such as as a raw material for building materials such as gypsum board and cement, its application is limited due to harmful impurities such as heavy metals. If it is not utilized, it will cause a waste of calcium and sulfur resources. Therefore, it is very necessary to develop a method that can solve the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide a method for treating gypsum solid waste from smelting flue gas desulfurization at low cost by using a copper flash converting furnace.

[0006] The object of the present invention is achieved in that the method for treating smelting flue gas desulfurization gypsum solid waste at low cost using a copper flash converting furnace comprises pretreatment and converting steps, specifically comprising: A. Pre-treatment: 1) crushing the desulfurized gypsum to obtain material a; 2) Grind the copper matte to a particle size of ≤0.1 mm to obtain material b; B. Blowing: After mixing material a and material b evenly, carry out flash blowing of matte under oxygen-rich conditions to obtain crude copper and slag.

[0007] Copper flash converting is a closed converting technology. Flash converting is to grind the high-grade copper matte (containing 68% to 70% copper) produced by the smelting furnace, dry it, and spray it into the tower from the top of the reaction tower together with lime (limestone), converting smoke and oxygen-enriched air with an oxygen concentration of 75% to 85%. Copper matte powder particles have a large specific surface area. In a strong oxidizing atmosphere, the oxidation process of ferrous sulfide and impurities such as lead, zinc, and bismuth in the copper matte only takes about 3 seconds to complete. During the converting process, CaO is used as a flux to carry out slag-forming reaction to obtain a slag with the main FeO component and containing some impurity elements and a small amount of copper. Overoxidized Cu 2 O and unoxidized Cu 2 S reacts with each other to obtain crude copper with a purity of about 99%. The flue gas produced is diluted and sent to the acid plant after passing through the waste heat boiler and the electric dust collector. Compared with the traditional converter blowing, it has the advantages of strong production capacity, low environmental pollution, low production cost, high production efficiency and strong adaptability to copper matte.

[0008] principle: In copper flash smelting, lime or limestone is usually used as calcium flux. At temperatures above 1200°C, limestone decomposes into CaO and CO. 2 : CaCO3 =CaO+CO 2 Desulfurized gypsum replaces lime or limestone. At a temperature of 1350-1400℃, the main component calcium sulfate is thermally decomposed: 2CaSO 4 =2CaO+2SO 2 +O 2 At the same time, calcium sulfate can also react with metal oxides: 3CaSO 4 +PbS=3CaO+PbO+4SO 2 3CaSO 4 + ZnS = 3CaO + ZnO + 4SO 2 3CaSO 4 +FeS=3CaO+FeO+4SO 2 5CaSO 4 +FeS=5CaO+FeO+7SO 2 9CaSO 4 +Sb 2 S 3 =9CaO+Sb 2 O 3 +12SO 2 The present invention is a method for low-cost treatment of flue gas desulfurization gypsum using a copper flash converting furnace, and belongs to the technical field of pyrometallurgy. The present invention uses flue gas desulfurization gypsum to replace limestone or calcium oxide as a smelting flux, calculates the amount of desulfurized gypsum according to the content of the copper matte entering the furnace in the copper flash converting process, the processing volume and the amount of calcium oxide added to the flux, and performs oxygen-enriched converting at 1200-1500°C. In the existing process, the present invention uses desulfurized gypsum solid waste to replace the calcium oxide flux, and fully utilizes the oxidation reaction heat in the pyrometallurgical converting process to decompose the desulfurized gypsum into calcium oxide and SO 2 and O 2 Characteristics of flue gas, by-product SO 2 Can reduce the cost of flue gas acid production, 2 Strengthening the smelting process enables low-cost disposal of desulfurized gypsum solid waste and efficient utilization of resources without changing the original process or equipment. DETAILED DESCRIPTION

[0009] The specific embodiments of the present invention are further described below in conjunction with the examples. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0010] The method for treating gypsum solid waste from flue gas desulfurization at low cost by using a copper flash converting furnace of the present invention comprises pretreatment and converting steps, specifically comprising: A. Pre-treatment: 1) crushing the desulfurized gypsum to obtain material a; 2) Grind the copper matte to a particle size of ≤0.1 mm to obtain material b; B. Blowing: After mixing material a and material b evenly, carry out flash blowing of matte under oxygen-rich conditions to obtain crude copper and slag.

[0011] The particle size of the crushed particles in step A1) is ≤1 mm.

[0012] In step B, the moisture content of material a needs to be controlled to ≤0.3% before entering the furnace.

[0013] The concentration of oxygen enrichment in step B is 74~86%.

[0014] The blowing temperature in step B is 1200-1500°C.

[0015] The present invention is further described below with specific implementation cases: Example 1 The composition of the added copper matte and desulfurized gypsum is shown in the following table: Table 1 Main components of copper matte (wt%) Table 2 The main chemical composition of desulfurized gypsum (wt%): The blowing adopts the iron-copper-calcium slag system; according to the composition and processing volume of the matte copper and the main component content of the designed slag, the amount of calcium to be added to the slag-making agent is calculated. According to the amount of calcium added to the slag-making agent and the calcium content of the desulfurized gypsum, the amount of desulfurized gypsum is calculated. Then, 1000g of the matte copper powder with the above composition is weighed, and 74.96g of the desulfurized gypsum with the composition described in Table 3 is added to replace 63.17g of 80% grade limestone. Mix evenly, and heat at a temperature above 1250℃ with 80%O 2 The matte was flash blown with oxygen-rich air. 570.1g of crude copper was obtained, with a direct copper recovery rate of 83.21%; 195.13g of slag, containing 3.04wt% Cu2, 12.77wt% CaO, and 1.14wt% Fe3. Compared with using limestone as a calcium flux, CO emissions are reduced. 2 22.24g, more SO 2 36.74g, SO in flue gas 2 The content increased by 8.09%. The slag from matte blowing is returned to the copper flash smelting oxidation matte making process for treatment.

[0016] Example 2 Add the matte with the main ingredients shown in the following table and the desulfurized gypsum of Example 1: Table 3 Main components of copper matte (wt%) The blowing adopts the iron-copper-calcium slag system; the amount of calcium to be added to the slag-making agent is calculated according to the composition and processing volume of the matte copper and the main component content of the designed slag. According to the amount of calcium added in the slag-making agent and the calcium content of the desulfurized gypsum, the amount of desulfurized gypsum is calculated. Then, 1000g of the matte copper powder with the above composition is weighed and 75.41g of the desulfurized gypsum with the composition described in Example 1 is added to replace the lime flux of 90% CaO. The mixture is uniformly mixed and heated at a temperature above 1250℃ with 80% O 2 The copper matte was flash blown with oxygen-rich air. 560.4g of crude copper was obtained, with a direct copper recovery rate of 82.03%; 187.25g of slag, containing 3.76wt% of Cu2, 9.76wt% of CaO, and 3.41wt% of Fe3. Compared with using lime as a calcium flux, more SO 2 36.96g, SO in flue gas 2 The content increased by 8.10%. The slag from matte blowing is returned to the copper flash smelting oxidation matte making process for treatment.

Claims

1. A method for treating gypsum solid waste from flue gas desulfurization using a copper flash converting furnace at low cost, characterized in that: The method for treating gypsum solid waste from flue gas desulfurization at low cost using a copper flash converting furnace comprises pre-treatment and converting steps, specifically including: A. Pre-treatment: 1) crushing the desulfurized gypsum to obtain material a; 2) Grind the copper matte to a particle size of ≤0.1 mm to obtain material b; B. Blowing: After mixing material a and material b evenly, carry out flash blowing of matte under oxygen-rich conditions to obtain crude copper and slag.

2. The method for treating gypsum solid waste from smelting flue gas desulfurization using a copper flash converting furnace at low cost according to claim 1, characterized in that: The particle size of the crushed particles in step A1) is ≤1 mm.

3. The method for treating gypsum solid waste from smelting flue gas desulfurization using a copper flash converting furnace at low cost according to claim 1, characterized in that: In step B, the moisture content of material a needs to be controlled to ≤0.3% before entering the furnace.

4. The method for treating gypsum solid waste from smelting flue gas desulfurization using a copper flash converting furnace at low cost according to claim 1, characterized in that: The concentration of oxygen enrichment in step B is 74~86%.

5. The method for treating gypsum solid waste from smelting flue gas desulfurization using a copper flash converting furnace at low cost according to claim 1, characterized in that: The blowing temperature in step B is 1200-1500°C.

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