Copper sulfide nickel ore beneficiation
Most of this type of ore is magma-dispersed copper-nickel ore, in which rich ore containing more than 3% of nickel can be directly smelted; ore containing less than 3% of nickel needs beneficiation.
Then need to be treated.
(1) Mineral composition and beneficiation method of copper sulfide nickel ore
Such common metal ore minerals: pyrrhotite, pentlandite and chalcopyrite, in addition to magnetite, pyrite, titanium, iron, chromium iron, copper ink, blue copper, chalcocite, bornite, and platinum group minerals; gangue minerals are: olivine, pyroxenes, plagioclase feldspar, talc, serpentine, chlorite, and mica stone from the sun, and sometimes silica and carbon Acid salt, etc.
Copper in copper-nickel ore mainly exists in the form of chalcopyrite; while nickel is mainly in the form of free nickel sulfide such as pentlandite, sulphur-nickel ore, and sulphur-nickel-iron ore, and a considerable part of nickel is present as a homogeneous image. In the pyrrhotite, there is also a small amount of nickel silicate.
The most suitable method for the beneficiation of copper-copper-nickel ore is flotation, and magnetic separation and re-election is usually an auxiliary beneficiation method.
(2) The floatability of main nickel minerals and the flotation characteristics of copper-nickel ore
Nickel pyrite, sulphur nickel ore and nickel-containing pyrrhotite can be effectively floated by high-grade xanthate such as butyl or pentyl. The floatability of pentlandite and needle sulphur nickel ore is between chalcopyrite and pyrrhotite. Nickel pyrite can obtain better flotation in weakly acidic, weakly alkaline or neutral medium; needle sulfur nickel ore can also be better floated in butyl yellow drug in weakly acidic, neutral or weakly alkaline medium. Nickel-containing pyrrhotite is suitable for flotation in acidic or weakly acidic media, but the flotation rate is slower.
Nickel pyrite, sulphur nickel ore and nickel-bearing pyrrhotite can be suppressed by lime, but to varying degrees. Pyrrhotite is easier to suppress, while inhibition of pentlandite and needle sulphur nickel ore requires excess lime. Unlike pyrrhotite and pyrite, other bases do not inhibit pentlandite and sulphur nickel ore. Separation of nickel-pyrite and chalcopyrite by lime alone is not good enough, usually with a small amount of cyanide to suppress pentlandite. Nickel pyrite can be oxidized faster by oxygen in the air, and an iron hydroxide film is formed on the surface thereof, and the floatability is lowered. The pyrrhotite is oxidized faster in the air than the pentlandite. Copper sulphate is a nickel pyrite, especially an activator of pyrrhotite. After the nickel mineral is inhibited by lime (rather than by the oxide), it can be reactivated with copper sulfate. In order to improve the activation of nickel minerals by copper sulfate, it is sometimes necessary to add a small amount of sodium sulfide in advance.
Nickel silicate minerals are currently not selected by industrial flotation. Therefore, the amount of nickel silicate in the ore is an important factor affecting the recovery rate of nickel.
Based on the properties of copper-nickel ore, the flotation process has the following characteristics: the flotation process is simpler, the flotation time is longer, the number of selections is less, the concentrate is more dispersed, and the nickel minerals are recovered as early as possible; the nickel concentrate grade is generally It is 4~8%, and the highest is 13~15%. Removal of pyrrhotite and talc, chlorite, actinolite, serpentine, mica and other easy-floating gangue are the key to improving the quality of nickel concentrate; in order to strengthen the flotation of nickel minerals, mixed collectors are often used; In order to remove pyrrhotite, a combined flotation and magnetic separation process is often employed.
(3) Flotation process of copper-nickel ore
When flotation of copper-nickel ore, a collector and a foaming agent for flotation of copper sulfide minerals are often used. One of the basic principles for determining the flotation process is to allow copper to enter the nickel concentrate while avoiding nickel from entering the copper concentrate. Because the nickel in the copper concentrate loses a lot during the smelting process, the copper in the nickel concentrate can be recovered more completely. Copper-nickel ore flotation has the following four basic processes:
(4) Direct priority flotation or partial priority flotation process
When the copper content in the ore is much higher than the nickel content, this procedure can be used to select copper as a separate concentrate. The advantage of this process is that copper concentrates with lower nickel content can be obtained directly.
(5) Mixed flotation process
It is used to select ore containing copper lower than nickel, and the obtained copper-nickel mixed concentrate is directly smelted into high-ice nickel.
(6) Mixing flotation copper and nickel from the ore, and then separating the copper concentrate containing low nickel and the copper-containing nickel concentrate from the mixed concentrate. After the nickel concentrate is smelted, high ice nickel is obtained, and the high ice nickel is further subjected to flotation separation.
(7) Mix-Priority Flotation and Recover Part of Nickel from Mixed Flotation Tailings
When the floatability of various nickel minerals in the ore is greatly different, after the copper-nickel mixed flotation, the nickel-containing mineral with poor floatability is further recovered from the tailings.
(8) Copper-nickel separation
Copper is a harmful impurity in nickel smelting, and copper grade in copper-nickel ore has industrial recycling value. Therefore, copper-nickel separation technology is an important issue in copper-nickel ore beneficiation. The copper-nickel separation technology is divided into two types: copper-nickel mixed concentrate separation and high-ice nickel separation process. Generally, the ore of copper-nickel minerals having a relatively large particle size and not closely intertwined with each other mostly adopts a mixed concentrate separation method; and for ores having a fine grain size and densely embedded with each other, a high-ice nickel separation process is often used.
(9) Separation process of copper-nickel mixed concentrate
At present, the most common separation methods for this process are the lime-cyanide method and the lime-sodium sulfide method, and sometimes the slurry heating measures will improve the separation effect. In addition, there is a bisulfite method and the like.
(10) High ice nickel mixed concentrate separation process
The process has better technical and economic effects than the separation smelting and water smelting treatment methods, so it is widely used.
The composition of high-ice nickel is mainly copper sulfide (Cu2S) and nickel sulfide (Ni3S2), followed by Cu-Ni alloy, in addition to cobalt and platinum group metals and some iron impurities. The composition of high ice nickel can be artificially controlled during the smelting process. Iron content and cooling rate are the two main factors for high-ice nickel flotation separation. They not only affect the material composition of high-ice nickel, but also affect its crystal structure.
Iron is a harmful impurity in high-ice nickel separation flotation, which can complicate the composition of high-ice nickel. When the iron content is less than 1%, compounds similar to porphyrite and pentlandite will appear, which is not conducive to flotation and affects the recovery of cobalt. When the iron content is >4%, not only the composition of high ice nickel is more complicated. The crystal structure also becomes finer and is not conducive to flotation. Production experience shows that the iron content in high ice nickel is preferably controlled within the range of 2 to 4%.
The cooling rate of high ice nickel also has a great influence on its separation. When it is slowly cooled from 800 ° C to 200 ° C, the crystal grain size of copper and nickel minerals becomes coarser, especially when the slow cooling temperature drops to 510 ~ 520 ° C, the nickel sulfide crystallizes, from -NiS2 to a-Ni3S2 The copper sulfide dissolved in the nickel sulfide is precipitated, thereby facilitating the reduction of the copper content in the nickel sulfide ore. Therefore, ensuring the slow cooling rate of high ice nickel can improve the separation effect of high ice nickel flotation.
Nickel oxide ore processing
High nickel laterite nickel oxide ore is iron, low silicon-magnesium-containing nickel 1-2%; low nickel iron silicate containing high silica-magnesia, nickel 1.6 to 4.0%. At present, the development and utilization of nickel oxide ore is based on nickel laterite ore. Since nickel in nickel oxide ore is often dispersed in gangue minerals with the same type of similarity, and the particle size is very fine, it is difficult to obtain good effects by direct treatment by mechanical beneficiation method. After changing the mineral structure by roasting the ore, although good technical indicators can be obtained, the cost is high and it has not been used in industrial production.
At present, in the treatment of nickel oxide ore, the bulk rock briquettes with weak weathering and low nickel content are removed in advance by crushing, sieving, etc., and the enrichment is relatively low.
In recent years, due to the continuous development of nickel-smelting technology and the increase of nickel consumption and the continuous reduction of nickel-sulfur-rich resources, the development and utilization of nickel oxide ore has received increasing attention. Nickel oxide deposits are generally shallowly buried and are suitable for large-scale open-pit mining and selective mining. Due to the lower mining cost, it has certain competitiveness compared with nickel sulfide ore.
The method of smelting and enriching nickel oxide ore can be divided into two major categories: fire method and wet method. Fire smelting can be divided into smelting smelting, ferronickel method and granule iron method. Wet smelting has reduction roasting - atmospheric ammonia leaching, high pressure acid leaching, and the like.
The rotary kiln milling method in pyrometallurgical smelting is an ancient method. The disadvantage is that the process is complicated, the granulated iron has low nickel content, the nickel recovery rate is low, and cobalt cannot be recovered. The electric furnace smelting is characterized by high nickel recovery rate and a part of drilling Nickel iron, which can be recovered during the refining process, is suitable for the treatment of sillimanite. When it is used in a laterite ore with high iron content, the recovery rate of iron is low and the electric energy consumption is large.
The atmospheric pressure ammonia leaching method in wet smelting has the disadvantage of low cobalt recovery rate; and the high pressure acid leaching method is suitable for treating nickel oxide ore containing low magnesium silicate.
At present, the treatment of nickel oxide mostly uses the electric furnace ice-making nickel method; and the rotary kiln refining iron method is rare. Wet smelting methods, such as ammonia leaching and acid leaching, have been applied industrially. Other new nickel smelting methods, such as high-temperature chlorination, sulphation roasting and other extraction processes, are still in the research stage and have made some progress.
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