Research and application of oxygen-enriched side-blowing direct lead smelting process

The traditional lead smelting process in my country is mainly sintering roasting-blast furnace reduction smelting. Since the sintering process produces low-concentration SO2 flue gas, it is not conducive to acid production and has serious environmental pollution. Blast furnace reduction smelting uses expensive metallurgical coke, which is a process that the country has clearly eliminated. At present, the most widely used lead smelting process in my country is oxygen bottom blowing oxidation smelting-blast furnace reduction smelting. This process basically solves the problem of low-concentration SO2 pollution, but the smelted high-lead slag ingot is then put into the blast furnace for reduction smelting, resulting in physical heat loss of high-lead slag, and blast furnace reduction smelting uses expensive metallurgical coke, and the production cost is relatively high.

The oxygen-enriched side-blowing molten pool smelting technology originated from the Vanyukov molten pool smelting technology and was initially used for copper smelting. In 2000, the oxygen-enriched side-blowing lead smelting technology was developed, and it has achieved good results in the industrialization process.

The oxygen-enriched side-blowing molten pool smelting technology has been successfully implemented in the field of copper-nickel ore smelting in my country. In 2010, my country began to use oxygen-enriched side-blowing molten pool smelting technology to treat sulfide copper-nickel ores. The enterprise was successfully put into production, and all technical and economic indicators are better than other copper-nickel ore smelting processes at present.

The oxygen-enriched side-blowing oxidation furnace and the oxygen-enriched side-blowing reduction furnace are the core equipment of the oxygen-enriched side-blowing direct lead smelting process. The two oxygen-enriched side-blowing furnaces are connected by a chute to achieve continuous operation. The primary crude lead and high-lead slag produced by the oxygen-enriched side-blowing oxidation furnace flow into the siphon chamber of the oxidation furnace, the primary crude lead is continuously discharged into the ingot through the siphon, and the high-lead slag is continuously discharged into the oxygen-enriched side-blowing reduction furnace through the chute. The secondary crude lead and the reduction smelting slag produced by the reduction furnace flow into the siphon chamber of the reduction furnace, the secondary crude lead is continuously discharged into the ingot through the siphon, and the reduction smelting slag is continuously discharged and sent to the fuming furnace for fuming and zinc extraction. The high-temperature flue gas produced by the three furnaces is recovered through the waste heat boiler. The high-temperature flue gas of the oxygen-enriched side-blowing oxidation furnace is sent to the acid-making system after passing through the waste heat boiler and the electric dust collector. The high-temperature flue gas of the reduction furnace and the fuming furnace can be discharged after simple desulfurization treatment after passing through the waste heat boiler and the bag filter. The smoke dust recovered by the oxygen-enriched side-blowing oxidation furnace and the reduction furnace is returned to the batching system. The main component of the smoke dust recovered by the fuming furnace is ZnO, which can be sold as the final product.

Oxygen-enriched side-blowing oxidation smelting process

Lead concentrate, flux, return material, and crushed coal are continuously added to the furnace from the top charging port of the oxygen-enriched side-blowing oxidation furnace through a metering belt, 45%. 85% of the oxygen-enriched air is blown into the slag layer in the furnace from the primary air nozzles on both sides of the furnace body. The melt is strongly stirred under the action of the oxygen-enriched air, and the lead sulfide concentrate reacts rapidly to generate primary crude lead and high-lead slag. The crude lead and high-lead slag flow into the siphon chamber at one end of the oxidation furnace for further clarification and separation. The primary crude lead is continuously discharged from the siphon outlet on one side of the siphon chamber to cast ingots, and the high-lead slag is continuously discharged from the slag outlet at one end of the siphon chamber and flows into the oxygen-enriched side-blowing reduction furnace through the chute. In order to fully burn the combustible components in the high-temperature flue gas of the oxidation furnace, a certain amount of air is blown in from the secondary air nozzles on both sides of the furnace body. The high-temperature flue gas produced by the oxidation furnace is discharged from the exhaust port on the top of the furnace and enters the waste heat boiler to recover waste heat. The flue gas enters the electrostatic precipitator after passing through the waste heat boiler and finally sent to the acid-making system.

The smoke recovered by the waste heat boiler and the electrostatic precipitator returns to the batching system. The primary crude lead yield of the oxygen-enriched side-blowing oxidation furnace is related to the grade of the lead concentrate. The higher the grade, the higher the primary crude lead yield. Generally, the primary crude lead yield is about 50% lead in the lead concentrate. In order to control the volatilization of PbS, the melting point of the oxidation slag should be controlled not higher than 1000℃ during the oxidation smelting process, and CaO/SiO: 0.5-0.7 is appropriate. The oxygen-enriched air pressure is ~0.1MPa, and the oxygen-to-material ratio is determined according to the composition of the lead concentrate.

Oxygen-enriched side-blowing reduction smelting process

The high-lead slag generated by the oxygen-enriched side-blowing oxidation furnace flows into the oxygen-enriched side-blowing reduction furnace through the chute. The flux and crushed coal are continuously added into the furnace from the charging port on the top of the reduction furnace through the metering belt. The oxygen-enriched air is blown into the slag layer in the furnace from the primary air nozzles on both sides of the furnace body. The melt is strongly stirred under the action of the oxygen-enriched air. The high-lead slag, crushed coal and flux are quickly mixed and evenly mixed, and the reaction generates crude lead and slag. The lead droplets collide with each other and grow. The lead droplets gradually sink into the area with weak turbulence below the air nozzle. The secondary crude lead and slag flow into the siphon chamber for further clarification and separation. The secondary crude lead is continuously discharged from the siphon discharge port on one side of the siphon chamber. The reduction smelting slag is continuously discharged from the slag discharge port at one end of the siphon chamber for fume extraction and zinc extraction. The high-temperature flue gas of the reduction furnace contains a certain amount of combustible components (mainly CO). In order to fully burn the combustible components in the flue gas, a certain amount of air is blown into the secondary air nozzles on both sides of the reduction furnace body to make them fully burn. The high-temperature flue gas produced by the reduction furnace enters the waste heat boiler to recover waste heat, then enters the bag dust collector to collect dust, and finally empties. The smoke recovered by the waste heat boiler and the bag dust collector is returned to the batching. 2

Application prospects of oxygen-enriched side-blowing direct lead smelting process

Although the traditional sintering-blast furnace reduction process is mature, it has serious environmental pollution and high energy consumption, and is a process that the country has clearly eliminated. Some of the lead smelting methods introduced from abroad in my country have been discontinued (QSL), and some are still in operation. Due to certain defects, they have not been promoted. The Kivcet method under construction is expected to achieve good implementation results. The SKS method, which is currently widely used in domestic lead smelting processes, also has certain defects, such as high requirements for the grade of lead concentrate, high physical heat loss of lead slag, expensive metallurgical coke as the reducing agent, and short service life of the oxygen spray gun, which needs to be further improved and improved.

The oxygen-enriched side-blowing direct lead smelting process is a lead smelting method independently developed by my country with independent intellectual property rights. Practice shows that this method has the advantages of low investment, wide adaptability of raw materials, low energy consumption, good environment, low labor intensity, and continuous operation. The oxygen enriched side-blowing reduction section can directly replace the current SKS blast furnace reduction process, which is convenient for the technical transformation of the SKS blast furnace reduction section, eliminating the high-lead slag ingot casting process, and the liquid high-lead slag is directly reduced in the oxygen-enriched side-blowing reduction furnace. The reducing agent is coal instead of coke, which reduces production costs. As an advanced lead smelting method, the oxygen-enriched side-blowing direct lead smelting process has broad application prospects.