blast furnace is widely used in the rough refining process of copper, lead, lead, zinc, antimony and other metals.
blast furnace is composed of top, shaft, bed (also called throat), hearth and tuyere device.
solid materials such as smelting burden (concentrate, sinter, etc.), coke, flux and reverse material are added from the top of the furnace, and the high-pressure air blown in the tuyere device at the lower side of the furnace shaft reacts with the downward materials in the process of going up, such as melting, oxidation, reduction, etc., to complete the smelting process, and liquid metal, matte and slag are discharged from the throat or hearth at the lower part of the furnace. At present, most of them are closed roofs, and the furnace body is full of water jackets. Refractory materials are only used in the throat and hearth. Because its slag belongs to alkaline slag, magnesia brick, magnesia-chrome brick and alumina-chrome brick are mainly used in the throat. Magnesia brick, magnesia-chrome brick and alumina-chrome brick are used for hearth side wall and upper part of furnace bottom; The bottom of the furnace is built into an inverted arch.
Second, reverberatory furnace
The operating temperature of reverberatory furnace head is generally 14 ~ 15℃, and the temperature of flue gas discharged from furnace is generally 115 ~ 12℃. The bottom of the furnace is asbestos board, thermal insulation brick layer, clay brick layer, magnesia-alumina brick or magnesia brick layer from bottom to top. The furnace walls are mostly made of magnesia-alumina bricks or magnesia bricks, and some important parts are built with magnesia-chrome bricks to prolong their service life, while the exterior walls are generally made of clay bricks. The ceiling adopts hanging roof, and the roof of small reverberatory furnace adopts brick arch, and the vault is made of magnesia-alumina brick.
Most lead (copper) smelting plants in China adopt the traditional sintering-blast furnace smelting process, because it has the following defects:
a, sulfur combustion is not sufficient in the sintering process, and the return material ratio is high;
b, the content of lead (copper) in blast furnace charge is low;
c, a lot of smoke pollutes the environment.
Therefore, people have been trying to explore a new process of lead smelting, and its purpose is nothing more than two aspects:
1. Smelting with reaction heat;
2. replace the original multi-step process with one-step process.
foreign countries have successfully developed new lead smelting furnaces and new processes, such as isa furnace, caldo furnace, QSL method, kifset method, siro method and oxygen-enriched lead smelting furnace.
iii. isa furnace (osmet furnace)
the isa furnace body is a simple vertical cylinder, and its technical core is the submerged top-blown combustion lance. based on years of small-scale experimental research, the isa smelter built a lead smelting isa furnace with a capacity of 5T/H in 1983.
the melting pool temperature is 117~12℃. The process of Aisa smelting: the furnace body is a vertical cylindrical spray gun with refractory lining, which is inserted into the furnace from the center of the furnace top. The head of the spray gun is immersed in the slag layer of the molten pool. The air or oxygen-enriched air needed for smelting process is sent to the liquid layer below the slag surface through the spray gun to form a molten pool with strong agitation. The charge is added from the furnace top and directly falls into the molten pool with strong agitation, and is quickly involved in the melt to react with the blown oxygen, and the charge is rapidly melted to form.
Because the lead (copper) smelting process in Aisa furnace is characterized by short mixing time of materials, and the molten metal, slag and acid gas are strongly stirred in the furnace, its working environment is much harsher than that of the traditional lead (copper) smelting process:
a, the refractory lining is strongly washed by molten lead (copper), slag and acid gas;
chemical erosion and infiltration of b and americium on refractory lining;
c, thermal stress damage.
Therefore, the refractory lining of lead (copper) smelting in Aisa furnace must have the following excellent performance, in order to achieve the goals of long life, high efficiency and low consumption of the furnace:
a, it has high compressive strength at room temperature and high temperature, and low porosity to resist the erosion of materials, molten metal and slag;
b, made of high-quality and high-purity raw materials, the product contains few low-melting substances, which can effectively resist the deterioration and damage caused by the chemical reaction between the environment and the furnace lining and improve the permeability resistance;
c, with excellent thermal shock stability and thermal stress (stress damage caused by temperature change is slight).
iv. Kaldor furnace
The main factors causing the damage of refractories for Kaldor furnace and the requirements for refractories are the same as those for Aisa furnace.
Kaldor furnace, also known as oxygen oblique blowing converter, increases the contact between liquid metal and liquid slag and improves the reaction efficiency because the furnace body tilts and rotates. Due to the rotation of the furnace body, the furnace body is evenly heated and corroded, which is beneficial to prolong the service life of the furnace.
Because oxygen is used, both smelting and blowing are carried out in the same furnace, so the smelting process is strengthened, the process is shortened, and the SO2 concentration in the flue gas is increased.
it is very important to choose the shape and size of the furnace inner chamber correctly for the smooth chemical reaction in the smelting process of Caldo furnace, reducing splashing, reducing the erosion of the bottom of the furnace, and being convenient to manufacture and install.
Blowing is carried out at a high temperature of about 11 ~ 13℃, so in order to ensure a certain furnace life, it is necessary to choose a reasonable lining material and determine a strict masonry method.
refractory materials with different thicknesses and materials should be selected according to the working environment and main erosion of each part in the design of the lining, so as to achieve the most reasonable configuration and reduce the cost; However, considering that the erosion rate of Kaldor furnace is relatively fast on average (the service life is 2 ~ 3 months), and for the standardization and convenience of on-site masonry management and the international standardization trend, the design with the same thickness and material is adopted, and the brick type is reduced. If the buyer has other requirements, it can be designed according to the buyer's requirements.
5. Oxygen bottom blowing furnace
1. QLS method
QLS method completes the oxidation and reduction reaction in the same reactor, and the reaction process is actually divided into two steps. Whether the design and configuration of the lining is reasonable or not is directly related to the life of the furnace; The design and configuration of the lining includes two aspects: one is to determine the reasonable structure and size; The second is the correct choice of refractories. QLS method is only available in silver in China, the lining thickness is 35mm, and the upper part of the molten pool is made of semi-fused magnesia-chrome bricks. The bottom of the molten pool is LDM Ge-26, which is fused and combined with magnesia-chrome brick.
2. Oxygen-enriched lead smelting furnace with gas bottom blowing
The oxygen bottom blowing oxygen-enriched lead smelting furnace is a horizontal cylindrical reaction furnace. Lzmge-18 directly bonded with magnesia-chrome bricks is selected for the upper part of the molten pool; At the bottom of the molten pool, LDM Ge-18, a semi-fused magnesia-chrome brick, is selected. Or LDM ge-18, a semi-re-bonded magnesia-chrome brick, is completely selected. The total dosage is about 16 tons.
VI. Volatilization kiln
Volatilization kiln is a rotary kiln for treating leaching residue and recovering valuable metals such as Zn, Pb, In and Ge.
The characteristic of the volatilization kiln is that the masonry of the kiln rotates with the kiln shell at high temperature, and it is in a state of vibration for a long time, and at the same time it has to bear the wear and impact of the burden; The damage of refractories mainly shows as follows:
(1) Corrosion of molten slag and metal.
(2) mechanical wear.
(3) Under the action of high temperature, the temperature of the intermittent reaction zone in the kiln is as high as 13 ~ 15℃.
Therefore, alumina-chrome slag brick or magnesia-alumina-chrome brick is mainly used in the intermittent reaction zone in the kiln to prolong the service life of the kiln lining.
The characteristics of Mg-Al-Cr brick are as follows:
First, large particles of pre-synthesized spinel are added in the production, and micro-cracks are generated in it by using the expansion inconsistency of various minerals at high temperature, thus improving the thermal shock stability of the product;
Secondly, the chromite contains Fe2O3, which diffuses into MgO, thus enhancing the direct bonding between periclase and magnesia-alumina spinel, promoting the bonding between particles and matrix, and improving the high-temperature strength of the material;
thirdly, chromite is added, in which Cr2O3 forms a continuous solid solution with Al2O3 and MgO, which improves the compactness and wear resistance of the material.
VII. Tilting furnace
In order to treat coarse copper, Guixi Smelter introduced the patented tilting furnace technology of MAERZ Company in Germany, including tilting furnace body, combustion system, ingot casting system, waste heat boiler, dust collection system and other auxiliary facilities.
the tilting furnace has the characteristics that reverberatory furnace can feed and remove slag, and rotary anode furnace can change the furnace position according to different operation cycles, with high mechanization and automation (hydraulic equipment is used for tilting, and flexible and fast special feeder is used for feeding), high combustion efficiency and low labor intensity for workers. The 35-ton tilting furnace in Guixi Smelter is the largest model at present, which can handle 1, tons of copper-bearing materials every year. Refractory materials selected are fused-bonded magnesia-chrome bricks or fused-semi-bonded magnesia-chrome bricks, and the content of Cr2O3 is above 18.
VIII. Flash Furnace
The flash furnace is an intensive smelting equipment for treating powdered sulfide minerals invented by Otto Kunpu Company of Finland, which generally consists of four main parts, namely concentrate nozzle, reaction tower, sedimentation tank and ascending flue. The dried furnace charge and preheated air are mixed through the concentrate nozzle and injected into the reaction tower at high speed. Under the action of high temperature, the reactions such as oxidative desulfurization, melting and slagging are rapidly carried out. After the formed melt enters the sedimentation tank, the slagging process is further completed and separated into enriched metal products and slag, and the molten gas product is discharged from the ascending flue.
refractory materials used in concentrate nozzles are generally high-alumina refractory castables or ramming materials.
the reaction tower is the main place for smelting reaction in flash furnace. The upper temperature is about 9 ~ 11℃, and the lower temperature can reach 135 ~ 155℃. Refractory materials are required to be resistant to high temperature, erosion, erosion and high temperature stability. The temperature of the top of the reaction tower and the upper tower wall is low, and the direct bonded magnesia-chrome brick is generally used. The middle and lower tower walls are made of fused magnesia-chrome bricks or fused magnesia-chrome bricks.
9. Noranda Furnace
In order to improve production capacity and environmental protection, Daye Nonferrous Metals Co., Ltd. built a new Noranda smelting process. After it was put into operation in 1997, it formed a production capacity of 15, tons of crude copper.
Noranda smelting process is developed by Noranda Company in Canada. It is a horizontal cylindrical reactor, which belongs to oxygen-enriched molten pool smelting. The concentrate drying, roasting, smelting and blowing slagging processes are completed in one reactor. Magnesia-chrome brick 18 is semi-combined with electric melting at the molten pool and slag line, and other parts are directly combined with Magnesia-chrome brick 16.
X. Converter
Most of the smelting process from copper sulfur to crude copper is carried out in the converter, and so is nickel smelting.
The converter is a horizontal cylindrical cylinder. The steel plate cylinder is lined with refractory material, and there is a furnace mouth for feeding and discharging materials above it, and there are a series of tuyeres on one side along the length direction. Most of the burden added to the converter is liquid copper sulfur or low nickel matte, which is subjected to desulfurization and slagging reaction under the action of blowing high-pressure air into the tuyere. The whole process is an autothermal smelting process without additional fuel, and the flue gas generated in the reaction process is continuously ejected from the furnace mouth and enters the dust collection and acid making system along the hood; Slag generated in the reaction process is periodically stopped, and then the furnace body is tilted from the furnace mouth to the outlet; The final product (coarse copper or high nickel matte) is also tilted from the furnace mouth to the outlet after the wind stops.
after blowing for a period of time, it is necessary to stop the wind to pour slag from the furnace mouth, and then add a batch of copper matte for blowing. This cycle is repeated several times until the predetermined copper matte is added and all the copper matte is blown into coarse copper. During this cycle, the converter temperature fluctuates between 8 ~ 15℃, and some cold materials and quartz stone are added during the smelting process.
The refractory material of converter is divided into tuyere, tuyere area, furnace mouth, furnace body and end wall. The tuyere is made of fused magnesia-chrome brick 26, and the tuyere area, furnace mouth, furnace body and end wall are made of fused magnesia-chrome brick 16 or fused semi-fused magnesia-chrome brick 16.
11. Anode furnace (refining furnace)
Anode furnace, also called rotary refining furnace, is suitable for refining molten crude copper.
The refining operations include feeding, oxidation, reduction and casting, and the product is anode plate. A furnace mouth is arranged on the cylindrical furnace body for charging and discharging copper, a small amount of tuyeres are arranged on the side of the furnace body, high-pressure air is introduced into the oxidation stage, and a reducing agent is introduced in the reduction period; The tuyere is placed above the melting surface when it is not in operation, and the furnace is tilted to bury the tuyere in the melting body when it is in redox operation.
firstly, the furnace temperature of anode furnace is higher than 135℃, which is different from fixed furnace in that there is no fixed molten pool (slag) line, and the erosion of slag and the erosion of molten metal almost involve more than 2/3 of the inner surface of the furnace;
Secondly, because the furnace needs to rotate frequently, the masonry and the steel shell must be in close contact, so as to increase the static friction between the masonry and the steel shell and overcome the rotating torque to maintain the stability of the masonry, so there is no light heat insulation layer;
thirdly, in order to reduce the load of masonry (to reduce the load of supporting devices and reduce the power consumption of transmission), the thickness of masonry layer should be reduced as much as possible under the condition that the surface temperature of steel shell allows (3℃).
In addition, in the two impact zones of charging, considering the influence of temperature fluctuation during charging, semi-fused magnesia-chrome bricks are also selected in this area. Because of the convenient structure and construction, the combustion port and flue gas outlet are tied with magnesia-chrome ramming material.