At present, the processing technologies of nickel oxide ore in the world can be summed up in three categories: fire process, wet process and fire-wet process. The pyrometallurgical process can also be divided into the process of reducing smelting and producing ferronickel and the process of reducing the smelting and smelting to produce niobium, according to the products it produces. The wet process can be divided into an ammonia leaching process and an acid leaching process according to the different leaching solutions thereof. The combination of fire and wet process refers to the process of selecting useful products by means of beneficiation method after reduction and roasting of nickel oxide ore.
1. The pyrometallurgical process (1) Reduction smelting The production of ferro-nickel-iron pyrometallurgical processes is the most commonly used in the world for reducing smelting to produce ferro-nickel. Currently, at least 14 factories use reduced smelting to treat nickel oxides to produce nickel-iron. The annual nickel-iron production (including nickel) is about 250,000 tons, most of which are smelted using electric furnaces. There are only a few smaller plants that are smelted using blast furnaces.
The process of smelting and producing ferronickel in electric furnace is suitable for processing various types of nickel oxide ore. The scale of production can be decided according to the supply of raw materials and the storage of ore, etc., which may vary, and the particle size of the charge into the furnace is not strict. Requirements, powder and larger pieces of material can be directly processed. The only drawback to the production of ferronickel in electric furnace smelting is its high energy consumption.
Blast furnace smelting to produce nickel-iron has the advantages of small investment and low energy consumption, and is suitable for areas with small production scale, difficult power supply, and low nickel content in nickel oxide ores. Its disadvantages are poor adaptability to ore, stricter requirements for magnesium content, and the inability to process the ore, as well as strict requirements on the charge to the furnace.
(2) Reduction sulfidation smelting production Nickel sulphide reduction sulfidation smelting treatment Nickel oxide production Nickel bismuth was first used to treat nickel oxide ore, which was applied as early as the 1920s and 1930s, when blast furnace smelting was used. This process has the same disadvantages as the process of reducing smelting and producing nickel-iron in a blast furnace. Large-scale factories built after the 1970s have adopted the technology of electric furnace smelting to treat nickel oxide ore to produce nickel crucibles. At present, several of the largest factories with an annual nickel output of more than 40,000 tons are in Indonesia and New Caledonia. The amount of nickel produced from nickel oxide in the world is about 120,000 tons.
Reducing sulfiding smelting sulfiding agents are available from pyrite, gypsum, sulphur and sulphur-containing nickel raw materials. The advantage of using sulfur as a vulcanizing agent is simple and easy, and does not have a negative impact on the smelting process (ie does not affect the slag composition, does not affect the processing capacity, does not increase power consumption), but it is more expensive, the effective utilization of sulfur is not High, but also have a set of sulfur melting and transport spraying facilities. Sulfur is used as a vulcanizing agent in Indonesia and New Caledonia, which are owned by International Nickel Corporation (INCO). The sulfur is melted and sprayed in a controlled manner on the calcined kiln which is still at a certain temperature, so that iron and nickel are converted into sulphides, which are then sent to the electric furnace for smelting to produce low-nickel niobium. The source of sulfur is said to be the natural sulphur of the caldera and its price is low.
Nickel bismuth is produced by reduction smelting and smelting of nickel oxide ore, and its high nickel bismuth has great flexibility: the nickel oxide after calcination and desulphurization can be directly reduced and smelted to produce general nickel for the stainless steel industry; it can also be used as Nickel pellets and nickel powders are produced by pressure carbonyl refining of nickel raw materials; since the high nickel matte contains no copper, it can also be cast directly into an anode plate to produce nickel sulfide for electrolytic refining of nickel cathodes. In short, it can be further processed to produce various forms of nickel products, and the cobalt can be recovered.
2. Wet process (1) Ammonia leaching (Caron process)
The industrial process of treating nickel oxide ore by wet processing began in the 1940s. The ammonia leaching process was first used, ie, the nickel oxide ore was subjected to multiple stages of atmospheric ammonia leaching after drying and reduction roasting. The representative factory is the Cuban Nigallon nickel plant constructed in the United States. Ammonia leaching process nickel oxide ore, the product can be nickel salt, ammonia leaching treatment process is not suitable for the treatment of copper-containing and cobalt-containing high nickel oxide ore, as well as nickel, nickel, nickel, nickel, nickel and nickel blocks. The type (New Caledonia) nickel oxide ore is only suitable for treating the surface laterite, which greatly limits the development of the ammonia leaching process. In addition, the nickel-cobalt recovery rate of the ammonia leaching process is low, the total nickel recovery rate is only 75 to 80%, cobalt is about 40 to 50%. So far, only four factories in the world have used ammonia leaching to treat nickel oxide ores. They were all built before the 1970s. In the past 30 years, no new plant has used ammonia leaching.
(2) Acid leaching method Nickel, cobalt, and other valuable metals are dissolved together with iron and aluminum minerals in dilute sulfuric acid at 250 to 270°C and 4 to 5 MPa under high temperature and high pressure conditions. In the subsequent reaction, certain At pH and other conditions, impurities such as iron, aluminum, and silicon are hydrolyzed into the slag, and nickel and cobalt selectively enter the solution. The solution is extracted by solvent extraction, sulfide precipitation, and other techniques.
The industrial production of nickel oxide ore by the acid leaching process began in the 50s of the last century. The representative factory at that time was the Cuban Mao A nickel smelter, which was also designed and constructed by the United States. The acid leaching process is suitable for treating nickel oxide ore with low magnesium content. An excessively high magnesium content in the ore will increase the acid consumption, increase the operating cost, and may also affect the process. If the cobalt content in the ore is high, the acid leaching process is more suitable. Not only the leaching rate of cobalt is higher than that of the ammonia leaching process, but also because the value of drilling is higher than that of nickel, the unit production cost of the acid leaching process is greatly reduced. Although the high-pressure acid leaching nickel leaching rate can reach more than 90%, the acid leaching process is also constrained by ore conditions. At present, there are only three factories in the world that use the acid leaching method to treat the nickel oxide ore, and due to the high temperature and high pressure processing conditions for the equipment. Demands are harsh and the operation is not very normal. In general, the development of the acid leaching process is not yet mature.
3. Wet-fired combination process Fire-wet process is a process that processes nickel oxide. At present, there is only Oyama Smelter of Nippon Yakim in the world. The main process is: raw ore fine grinding and pulverized coal mixed grouping, drying and high temperature reduction roasting of the ore ore, roasting ore group to grind again, ore slurry is subjected to beneficiation (re-election and magnetic separation) to obtain the nickel-iron alloy product. The most important feature of this process is its low production cost, 85% of energy in energy is provided by coal, and tons of coal is 160-180kg. The energy consumption of the pyrometallurgical process electric furnace smelting is over 80% provided by electric energy, and the electric power consumption per ton mine is 560-600 kWh. The difference between the two energy consumption costs is very large. According to the value of the current domestic market, the price difference between the two is 3-4 times. . However, there are still many problems in this process. Although the Dajiangshan smelter has been improved several times, the process technology is still not stable enough. After several decades, its production scale still stays at an annual output of about 10,000 tons of nickel. The key technology of this process is to control the temperature of the roasting process to control the mixing and preparation of pulverized coal and ore. From the viewpoint of energy conservation, low cost, and comprehensive utilization (handling low-grade nickel oxide ore) nickel resources, this process is worth further research and promotion. Russian researchers have conducted experimental studies on the use of isolated roasting of the Ural oxide nickel ore for flotation or magnetic separation. They believe that it is currently the only method that can reduce costs, save energy, and increase nickel production. It is suitable for any type of treatment. Nickel oxide ore.
The pyrometallurgical process to treat nickel oxide ore produces nickel-iron alloys with advantages such as short flow and high efficiency, but its energy consumption is high. The largest component of its operating cost is energy consumption. If electric furnace melting is used, electricity consumption alone accounts for the operating cost. 50%, coupled with the fuel consumption of the drying and roasting pretreatment process before the nickel oxide ore smelting, the energy cost in the operation cost may account for more than 65%, and the low-grade nickel laterite ore is treated by the pyrometallurgical process due to smelting The amount of ore is high in energy consumption and the cost of smelting is high. Therefore, the current pyrometallurgical process mainly deals with high-grade nickel laterite ores. At present, the main method of processing medium-low nickel laterite ores is the wet process. Although the cost is lower than that of the pyrometallurgical process, the wet process for treating the nickel oxide ores is complicated, the process is long, and the process conditions require high equipment. In summary, solving the problem of high energy consumption in the pyrometallurgical process and developing a new wet process to treat low-grade nickel laterite ore will be the development direction of nickel smelting in the future.
Stainless Steel Ball Valve
Stainless Steel Ball Valve, Stainless Steel Ball Valve by Flange, 2PC Threaded Stainless Steel Ball Valve
Ningbo RMI Plastic Co., Ltd. , http://www.rmiplast.com