1, an anode of nickel sulfide Preparation of anode nickel sulfide, nickel matte is first high secondary nickel sulfide flotation concentrate output, the reflected melting furnace, burning casting, slow cooling step of producing an anode having certain physical specifications The plate, the power supply is refined to produce electro-nickel, and also removes about 10% of impurities. Figure 1 shows the process flow of the secondary nickel concentrate smelting and casting.
1) The main raw material of the original molten cast nickel sulfide anode plate for the molten cast sulfide anode is the secondary nickel concentrate, in addition to the electrolytic residual plate and the cast casting return, the main chemical composition of which is shown in Table 1.
Table 1 Â Raw material composition (%) of cast nickel sulfide anode plate | ||||
raw material | Ni | Cu | Fe | S |
Secondary nickel concentrate | 63 | 3.5 | 1.8 | 26 |
Anode chip | 68 | 4 | 1.7 | twenty four |
Smoke | 20 | 1.4 | 3.5 | 8.4 |
[next]
The residual rate of nickel sulfide electrolysis is about 25%. During the electrolysis, the surface of the residual pole is provided with anode mud and some electrolyte. In order to prevent the occurrence of "shooting" accident in the furnace, the residual pole must also be naturally dried.
Return material is added to the main smoke produced nickel concentrate, produced at the anode unacceptable crusts or cast on the casting package, splashes and scattered on the ground expanded metal sulfide hyperplasia was picked out from the slag Metal materials, etc.
2) The fuel reverberatory melting smoke available coal, pulverized coal, heavy oil, natural gas and other fuel heating reported. Since the capacity of the melting reverberating furnace is small, the furnace temperature is high and the operation is intermittent, the fuel has a high calorific value and a small water, so that the heating rate is fast and easy to control and adjust. Jinchuan's nickel-melting reverberatory furnace uses heavy oil for heating, and the fuel rate is 165kg per ton of anode plate.
3) Casting production operation The material of the molten reverberatory furnace is powder and block. The bulk material has a residual pole and a block-shaped unqualified anode which is manually broken into 30-50 mm. The powdery material is a secondary nickel concentrate and soot after natural drying, and the two are mixed according to a certain proportion and then given by a disc. The feeder and belt conveyor are added to the reverberatory furnace. The principle is to add powder first, then add blocks.
The charge is melted in a high temperature and slightly oxidizing atmosphere. The furnace temperature is generally 1350 ° C, and the pressure is controlled to be slightly negative. After the charge is melted, due to the difference in density, a small amount of slag, sediment and the like caused by the raw material clamp float on the surface of the nickel crucible melt to form a molten cast slag, which needs to be periodically slag. The molten cast slag accounts for about 6% to 10% of the amount of the feed material. The amount of soot accounts for 3% to 4% of the amount of material in the furnace. The direct recovery of nickel is about 97%. The total recovery is above 98%.
When the nickel sulfide anode is cast, substantially zero pressure in the furnace is maintained. The released nickel sulfide melt flows into the intermediate casting package through the launder, and the worker controls the intermittent injection into the casting mold of the linear casting machine. The casting mainly controls the melt temperature, the mold temperature and the cooling rate of the anode plate.
After casting, the anode plate is cooled to 650-700 ° C in a mold, taken out, and slowly cooled in a thermal insulation pit to complete the phase transition of βNi 3 S 2 —β′Ni 3 S 2 . If the insulation control is not good, the anode plate will be brittle and crack, which will affect the electrolytic production. After 48 hours of slow cooling, the temperature dropped to 150-200 ° C. At this point, the crystal form transformation was completed before it was cooled to room temperature in air.
4) Chemical reaction of nickel sulfide anodic precipitation In order to ensure good solubility of the nickel sulfide anode and the quality of the cathode nickel, the components of the anode plate should be controlled within a certain range. Table 2 shows the chemical composition of the nickel sulfide anode plate.
Table 2 Chemical composition of nickel sulfide anode plate (%) | |||||||
work  plant | Ni | Cu | Co | Fe | S | Zn | Pb |
I factory | >65 | <5 | 0.8 to 1.0 | <1.9 | <25 | <0.004 | <0.005 |
II factory | 65~70 | <5 | 0.6 | 1.5 | 20~22 | 0.01~0.05 | Trace |
III factory | 62~65 | 3 to 5 | 0.6 to 0.8 | 2.5 to 3.0 | 22~23 | 0.025～0.05 | 0.03～0.05 |
The sulphur content of the anode plate has a great influence on the anode process. When S<20%, the anode plate will precipitate a metal phase during solidification. In the anodic reaction, the metal phase will preferentially dissolve, and a large amount of anode mud containing a high amount of Ni is produced; when S>25% is contained, the anode plate is brittle and brittle, and the anode acidification reaction is serious, which is also unfavorable for production.
Copper is the main harmful impurity of nickel sulfide anodes. Copper exists in the form of Cu 2 S in the anode plate. When the copper content is low, it has little effect on the dissolution rate of the nickel sulfide anode. When the copper content is higher than 10%, the Cu 2 S dissolves preferentially over Ni 3 S 2 and vulcanizes. Nickel anodic dissolution and electro-nickel quality have extremely adverse effects.
Low iron containing anode plate board electrolytic little effect, but will result in significantly increased anodizing, a rapid increase in cell voltage, the anode reaction of the corresponding acid made reinforcing iron is high, can cause serious Anodizing.
The anode plate also contains a certain amount of cobalt and a trace amount of lead , zinc, etc., due to the small content, it has little effect on the dissolution of the anode, mainly on the solution purification and cathode deposits.
2. Production and processing of the initial pole piece 1) Seed plate production The production of the seed plate groove is to provide the nickel starting piece as the initial cathode to the production tank. In addition to the titanium plate, the electroplating equipment and technical operating conditions of the seed tank are the same as those of the finished electrolytic cell. The number of plate electrolyzers is generally 1/10 of the number of electrolytic cells produced. Cathode, the period is 12 ~ 24h, the anode cycle tank voltage rises a lot, it is easy to cause anode passivation, and even cause anode smoke.
The plate production should take into account the difference in lattice parameters and thermal expansion coefficient between the mother plate and the deposited metal. The cathode (motherboard) of the seed groove is originally made of 3mm thick stainless steel plate. However, due to the trouble of "burning plate" and "sticking plate" on the surface of the stainless steel plate, it is now replaced by titanium material because of corrosion resistance of titanium material. Well, the coefficient of thermal expansion is large. Under certain conditions of temperature and poor nutrition, the initial piece is easy to fall off from the mother plate, and the use period is long, and the above-mentioned undesirable phenomenon is not easy to occur. Once it occurs, it can be used after treatment.
In order to prevent the occurrence of cracking and sticking, the dirt, dust and other dirt on the surface of the motherboard must be removed. Therefore, the titanium mother board should be treated with hot water at 65 ° C before each ditch. For a motherboard that uses more than one friend, special treatment is required before use. The specific method is to soak for 0.5 to 1 min in a solution containing 400 to 700 g/L of H2SO4, and then rinse the surface with hot water.
In order to prevent the precipitation of nickel around the periphery of the mother board, it is difficult to peel off the starting piece from the mother board, and both sides and the bottom side of the board must be edged. The current method is to use a grooved wood strip to clamp the bottom edge and a rubber strip to clamp the side edge. Although the operation is simple, the operation is too frequent, and the wood strip is expensive, and a more suitable method of wrapping and wrapping is to be sought. material.
2) Processing of the initial pole piece Since the first pole piece peeled off from the titanium mother board, the deposition time is short, the thickness is thin, the rigidity is poor, and it is easy to be deformed after the electrolytic cell is installed, so proper machining and surface treatment must be performed before the lower groove.
The work of peeling the starting piece is first to scald in the hot water tank to remove the surface adhering solution, and the peeled off initial piece is then pressed by the roll embossing machine, and then cut into 880 mm×860 mm on the shearing machine. The size of the size, and then use the nail headphones to rive the ears. In order to ensure that it is not easy to warp and deform after the lower groove, it is necessary to undergo secondary embossing to increase its rigidity. Finally, it is immersed in concentrated HCl (32% to 35%) solution for 3 to 5 minutes to remove surface dirt, and then rinsed with cold water. You can go down the slot.
Car Truck Tent,Camping Pickup Truck Bed Tent,Outdoor Car Tail Truck Tent,Waterproof Pickup Truck Tent
Shaoxing Haoto Trading Co.,Ltd , https://www.hotooutdoor.com