Wechat QR code
Wechat QR code
15311826613
Click to add WeChatIn the modern industrial system, nickel, as an important non-ferrous metal, is widely used in stainless steel, batteries, alloys and other fields. As an important source of nickel resources, the development of its metallurgical technology is of great significance to ensure the supply of nickel and promote the upgrading of related industries. At present, the common laterite nickel metallurgical technologies are mainly pyrometallurgy and hydrometallurgy. So what is the difference between the two? Let's learn about it together.
Rotary kiln-electric furnace process: This process is one of the mainstream pyrometallurgical processes for processing laterite nickel ore to produce nickel-iron alloy. First, the laterite nickel ore is dried and granulated, and then sent to the rotary kiln for pre-reduction, and part of the iron and nickel oxides in the ore are reduced at high temperature; then the pre-reduced material is sent to the electric furnace for deep reduction and refining to produce nickel-iron alloys of different grades. The RKEF process has the advantages of large production scale, stable product quality, and relatively low energy consumption, but it also has problems such as high investment cost and limited adaptability to ores.
Blast furnace smelting: Similar to the ironmaking process, laterite nickel ore is added to the blast furnace in a certain proportion with coke, flux, etc., and a reduction reaction is carried out at high temperature to produce nickel-iron alloy. The blast furnace smelting process is mature and has high production efficiency, but this method has poor adaptability to ores. It is generally suitable for processing laterite nickel ores with low nickel content and high iron content, and has high energy consumption and prominent environmental pollution problems.
High pressure acid leaching (HPAL): This is a relatively important hydrometallurgical technology. The laterite nickel ore is first crushed and then placed in an autoclave. Under the conditions of 240-265℃ and 4-5MP, it is leached with dilute sulfuric acid, so that nickel (Ni) and cobalt (Co) react with sulfuric acid to form soluble hydrogen sulfate into the solution, while impurities such as iron remain in the slag. After that, the leachate is subjected to subsequent operations such as neutralization and extraction to separate and purify metals such as nickel and cobalt. This technology is suitable for processing various types of laterite nickel ores, especially medium and low-grade ores, with high nickel and cobalt recovery rates, but the equipment investment is large, and special acid-resistant materials (such as titanium) are required to make autoclaves, and the sulfuric acid consumption is large. At the same time, a large amount of acidic waste slag will be produced, and the environmental protection treatment cost is high.
Atmospheric pressure acid leaching: There are sulfuric acid heap leaching and nitric acid heap leaching processes, which have simple processes, low energy consumption and low investment costs. Heap leaching is to pile up laterite nickel ore and leach it by spraying sulfuric acid or nitric acid solution. However, the leaching efficiency of this method is relatively low, the separation of the leachate is difficult, and the nickel content in the leaching slag is still high. It is generally suitable for processing limonite-type low-nickel ores.
Ammonia leaching method: First, the laterite nickel ore is reduced and roasted to reduce nickel to metallic nickel, and most of the iron is reduced to iron oxide (a small amount of iron oxide is reduced to metallic iron), and then the metallic nickel is leached with ammonia water. The ammonia leachate is treated by distillation to obtain nickel products. This process has a certain selectivity for ores and is suitable for specific types of laterite nickel ores. It is used in some special occasions, but the process is relatively complex and the operation requirements for links such as ammonia recovery are relatively high.
Pyrometallurgy: It is to extract metals from laterite nickel ore through high-temperature chemical reactions, separate metals such as nickel from their compounds by high-temperature reduction reactions, and purify them by means of differences in the physical and chemical properties of metals and impurities. For example, in the rotary kiln-electric furnace method, the laterite nickel ore is first dried and roasted in a rotary kiln for pre-reduction, and then smelted at high temperature in an electric furnace to obtain nickel-iron alloy.
Wet process: Based on the principle of chemical dissolution, acid (such as sulfuric acid) or ammonia and other reagents are used to react with metals such as nickel and cobalt in laterite nickel ore to dissolve them into the solution, and then the metal products are obtained through subsequent separation and purification operations. Like the high-pressure acid leaching process, nickel and cobalt are dissolved under specific conditions with sulfuric acid.
Pyrometallurgical process: Generally more suitable for processing laterite nickel ores with relatively high nickel grade (such as nickel>2%) and low cobalt content (cobalt<0.05%), such as medium-high nickel grade saprolitic ore.
Wet process: It has a wider adaptability to ore grades, especially suitable for processing medium-low grade laterite nickel ores, including limonite-type low-nickel ores. High-pressure acid leaching process can process various types of laterite nickel ores.
Pyrometallurgical process: The process is mature, the production efficiency is high, and it can be produced on a large scale; for specific types of ores, the nickel recovery rate is high, usually above 85%, and cobalt can be recovered at the same time; the output of nickel-iron alloy can be directly used as raw materials for the production of stainless steel, etc. However, it has high energy consumption, will produce a large amount of high-temperature waste gas, waste slag and other pollutants, and has great environmental pressure; the equipment investment is large.
Wet process: Relatively environmentally friendly, low energy consumption; can more effectively separate associated metals, such as cobalt; the product purity is high, and high-end products such as battery-grade nickel sulfate can be produced. However, the investment in high-pressure acid leaching equipment is huge, and the requirements for equipment materials are high; the reagent consumption is large, and the process flow is long and the production cycle is long.
Pyrometallurgy: mainly produces nickel-iron alloys, low-nickel mattes, etc., which are mostly used in the steel industry, stainless steel production and other fields.
Hydrometallurgy: can produce nickel sulfate, electrolytic nickel and other products, which are widely used in new energy batteries (such as lithium batteries), electroplating and other industries.
The above is an introduction to the pyrometallurgical and hydrometallurgical technologies of laterite nickel ore and the differences between the two. As an important source of global nickel resources, the selection of mineral processing and purification technology for laterite nickel ore is crucial to resource utilization efficiency, production cost and environmental impact. As two core technology systems, pyrometallurgy and hydrometallurgy each have distinct technical characteristics and application boundaries. In actual mineral processing plants, it is necessary to formulate suitable mineral processing and purification plans based on multi-dimensional factors such as ore properties, product demand, investment scale and environmental protection requirements.
CHAT
MESSAGE
Consult
Message
