Refractories for closed lead - zinc blast furnaces and oxygen bottom - blown lead converters
The lead - zinc closed blast furnace is a smelting method developed for lead - zinc mixed ore. The lead - zinc closed blast furnace mainly consists of a blast furnace and a condenser. It can smelt lead and zinc at the same time and has wide adaptability to raw materials. The charge of lead-zinc closed blast furnace is mainly lead-zinc sintered block ore, coke and flux. The principle for lead-zinc sinter with partial join inside the airtight blast furnace, coke was back into the metal, liquid lead into the hearth, zinc into gas with the furnace gas into the lead rain fog chamber (lead), condenser is condensed into liquid zinc, liquid zinc and lead into the separation chamber, the upper zinc with coarse zinc output, again into the crude zinc distillation device, and the lower lead liquid may continue to use back to the condenser.
The body of lead-zinc airtight blast furnace is airtight, and hot air is used at 800~850℃. The top of the furnace maintains a high temperature of 1050~1100℃, and the furnace charge carries out a strong physical and chemical reaction in the tuyere area, which can make the temperature of the coke area as high as 1400℃. The slag is mostly high calcium or high iron slag type and flows into the front bed at 1300~1350℃. The furnace gas with strong reducing properties containing zinc vapor flows into the condenser from the top of the furnace, and the temperature at the top surface of the furnace can reach 1030~1060℃. There is only slag in the hearth and lead from the front bed. The forebed of lead-zinc closed blast furnace is electric heating forebed, and its service life is lower than that of blast furnace, which is mainly caused by slag erosion and scouring of slag line. At present, the front bed of two lead-zinc closed blast furnaces in China is lined with chromium slag brick and aluminum-chromium titanium brick respectively. Although the furnace life can reach more than one year, it is still lower than the life of lead-zinc closed blast furnaces.
The hearth of the blast furnace is seriously eroded by alkaline slag, so the lining of the hearth is constructed by high quality magnesia-chrome brick with good resistance to FeO and CaO, and the furnace shell in the smelting area is cooled by spray water. Due to the high hardness of sintered block and coke, the furnace body is made of high quality aluminum brick or andalusite brick with good wear resistance (andalusite brick is a new variety developed by luoyang refractory material co., LTD. (referred to as luonai). The top of the furnace is made of high aluminum refractory castable with reinforced brick hanging. Condenser and rotor, due to the requirements of good thermal conductivity, erosion resistance, corrosion resistance, the use of silicon carbide refractory material.
Lead converter for oxygen bottom blowing --QSL method
The oxygen bottom blowing lead smelting method is one of the direct smelting methods of lead sulfide concentrate, which includes the German QSL method and the Chinese Shuikoushan (SKS) method. Their common characteristics are high utilization rate of oxygen and sulfur (98%~100%), high concentration of SO2 in flue gas (8%~11%), flexible operation of furnace, good working conditions and low cost.
QSL method
QSL method is one of the direct lead smelting methods. It is named after the first letter of the name of Prof. P.E.Queneau and R.Schuman and Lurgi, the process developer. Compared with the traditional lead smelting process, it eliminates the sintering process, so it has the advantages of short flow, high heat utilization rate, high SO2 concentration in flue gas, high sulfur utilization rate and better solve the environmental protection problems.
QSL reactor is the core equipment of oxygen bottom blowing direct lead smelting furnace. The reactor is composed of feeding oxidation zone, reduction zone, lead siphon zone, sediment slag zone and smoke vent. It is a horizontal cylinder with a section changing along a long axis. There is a partition wall in the furnace will be divided into oxidation melting area and slag reduction area; The lower part of the partition wall is provided with a hole for the melt to pass through, the furnace bottom of the oxidation zone is provided with a submerged oxidation nozzle, and the reduction zone is provided with a pulverized coal and oxygen enriched nozzle. Granular concentrate is injected from the top of the furnace in the oxidation zone, and oxygen is injected from the spray gun at the bottom. Melt desulfurization and smelting reaction are carried out at 1050~1100℃, and the lead liquid generated is collected at the bottom. The slag containing PBO passes through the slag dam and enters the reduction zone at 1150~1250℃. The slag is reduced to lead by carbon and flows back to the bottom of the oxidation zone. The molten lead and depleted slag are respectively released from both ends of the furnace in a countercurrent state, and the whole melting process is carried out in a closed furnace.
The melt temperature in the reactor bath is not very high and most of the melt in the bath is high lead slag. In some oxidized areas the slag contains about 40% lead. At the same time, there is strong agitation and splashing in the molten pool of the reactor, and the furnace lining is strongly scoured and eroded. In order to ensure the life of the furnace, we must choose high quality alkaline refractories with good slag resistance and scour resistance. In terms of the design of lining materials in QSL reactor, the upper part of the reactor is directly combined with High Purity Sinter brick, the molten particle is directly combined with magnesium-chrome brick DB505-B (Fused MgO-grain) to build the molten pool part, while the spray gun hole is completely Fused with magnesium-chrome brick BCF-3 (Fused MgCr-grain).
The upper lining of the oxygen bottom blown lead converter designed in China is constructed with directly combined magnesia-chrome bricks, the molten pool is constructed with half recombined magnesia-chrome bricks, and the nozzle hole area is constructed with imported bricks DB505-B and BCF-3.
ShuiKouShan method
The process also belongs to the oxygen bottom blowing bath melting. The research on this technology is a key scientific research project of the "7th Five-Year Plan" in China, which is the result of cooperation among scientific research, design, colleges and enterprises. In addition to the advantages shared by the QSL method, the Shuikoushan method has the special advantages of short process, low investment and fast start-up, which is suitable for small and medium-sized smelting enterprises.
Oxygen bottom blowing lead converter (reactor) is the key equipment of Shuikoushan process. The size of the reactor is 2.234m*7.89m, the inner section is non-equidiameter, the horizontal horizontal prevention, three oxygen lance are placed, the top is equipped with two air seal feeding ports, the siphon lead outlet is perpendicular to the reactor axis, the smoke outlet is a round copper water jacket, the upper end is equipped with water-cooled helicopter flue and sealed smoke cover.
Shuikoushan method uses two equipment to complete the oxidation and reduction process respectively. In the reactor to complete the oxidation reaction of lead sulfide concentrate, make high lead slag, and then into the depleted electric furnace with coal reduction. In this way, the characteristics of high oxygen utilization rate and fast reaction in the reactor can be brought into play, and high concentration of SO2 flue gas can be obtained.
Because Shuikoushan method and QSL method are both oxygen bottom blowing lead smelting method, their furnace lining materials are basically similar, mainly using high quality magnesium-chromium refractory materials.