   Commonly used refining gold crucible furnace can be divided into furnaces, converters and electric arc furnace three types. The crucible is generally used for the smelting of small amounts of gold mud and other materials, and is commonly used in small mines. The most commonly used are oil or natural gas fueled converters. The electric arc furnace was first developed from South Africa in recent years. The South African Anglo-American mining company's immersed three-phase electric arc furnace smelting cyanide gold mud was successful, and it is said that the cost can be reduced by 40% compared with the converter.
First, the furnace
   The picture below shows the simple structure of the oven.
   The furnace is made of ordinary clay- resistant bricks, and the upper part is smaller than the bottom and has a tapered shape. The bottom of the furnace is paved with 2 to 3 layers of refractory bricks. The brick joints are filled with refractory mud, and the brickwork and the shell are filled with asbestos ash or diatomaceous earth . The shell is made of 3 mm thick steel. The top of the furnace is crimped with refractory bricks to ensure that the flame can fill the entire furnace.
Crucible furnace commonly used heavy oil, diesel or coal gas as a fuel, the burner is disposed at a lower portion of the furnace according to the different parts of the Central or tangential. [next]
When the furnace is smelted, the charge is contained in the crucible. Made of graphite or refractory clay , the commonly used graphite crucibles come in a variety of sizes. When smelting with graphite crucible, it is best to lining a layer of refractory clay in the crucible. This is because graphite has a reducing effect on copper- lead oxide, which is not conducive to the slagging process. At the same time, slag-forming flux and oxidizing flux to graphite crucible Has a strong corrosive effect. If the refractory clay is not lined, a graphite crucible can only be used 2 to 3 times. One or several crucibles may be placed in the crucible according to the situation, and a refractory brick must be placed on the lower part of the crucible.
There are two ways to exhaust the furnace. One is that the upper wall of the furnace has a smoke outlet connected to the flue; the other is to leave a smoke exhaust port in the center of the furnace cover, and the furnace gas is exhausted through the hood. . The furnace cover is made of refractory clay bricks, which are then clamped with steel hoops or smashed with refractory concrete to form a unitary furnace cover.
The furnace is relatively simple, the laying of the lining is convenient, and the operation is easy to grasp. However, due to the opening and closing of the furnace cover, the loading and unloading of the hoe is performed manually, and the labor intensity is high and the conditions are relatively bad, so the large and medium-sized mines rarely use this. Type of furnace.
Second, the converter
   The furnace is actually a tilting reverberatory furnace. The figure below shows the basic structure of the converter.
(1) Structure of the converter [next]
The furnace shell of the converter is made of steel or cast steel, which can be made into a whole or a detachable two halves. The ends of the furnace shell have detachable end caps. A combustion hole is opened in the center of the end cap to allow the burner to be installed.
The furnace body is supported on the four rollers by two support rollers, and the angle of the support point is
(ii) Refractory lining of the converter
The lining of the furnace can be of various types. When the inner diameter of the shell is
Common refractory tile furnace brick high aluminum and magnesium brick. High alumina bricks have better adaptability to slag, and their performance also increases with the increase of Al 2 O 3 content in bricks. Magnesia bricks can also be used when the slag of the selected slag has a low degree of silicic acid. When building bricks, it is necessary to strictly control the masonry standards, and the bottom of the furnace should be thicker. Each brick must be strictly ground. Make sure the bricks are sewn during the masonry
It is a good idea to beat the integral lining with refractory material because the overall lining can reduce the retention of metal in the furnace. The beating method is easy to grasp, especially for small diameter furnaces. The ends of the lining lining are higher than the center, and the furnace is olive-shaped, which is conducive to the concentration of metal in the center of the furnace. When dumping, all the metal can be poured out.
The refractory material for the integral lining is usually made of aluminum silicate, and the higher the content of Al 2 O 3 is , the better. The table below shows the formulation of two lining materials.
Furnace lining
Furnace lining name Mullite High aluminum clinker ( Al 2 O 3 >70% ) | 3~7 cm 20~25% 25~35% | 1.5~3 mm 40~45% 30~40% | -0.088 mm 25~40% 30~40% | Phosphoric acid 8-12% 6-8% | water 2% 2% |
When the overall lining is beaten, a wooden core is placed in the furnace, and the wooden mold is not removed after being finished. As the oven progresses, the wood mold is burned. The furnace lining prepared with phosphate should be thoroughly mixed, no dry powder, and the doping should be strictly controlled. After mixing the materials, they should be trapped for 24 hours before use. Baking of linings made of aluminum silicate materials shall be carried out in accordance with the following requirements :
Low temperature drying: heat up to 5 to 15 ° C / hour to
High temperature heating: After drying, the temperature is raised to 100 to 150 ° C / hour to
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