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1. Vulcanization flotation method
(1) Conventional vulcanization flotation method
In this method, the copper oxide mineral is first vulcanized with sodium sulfide or other vulcanizing agent (such as sodium hydrosulfide), and then advanced yellow drug is used as a collector for flotation. When vulcanizing, the lower the pH of the slurry, the faster the vulcanization proceeds. The vulcanizing agent such as sodium sulfide is easily oxidized and has a short action time. Therefore, when the copper oxide ore is floated by a vulcanization method, the vulcanizing agent is preferably added. Ammonium sulfate and aluminum sulfate contribute to the vulcanization of oxidized minerals, so the addition of these two agents during vulcanization flotation can significantly improve the flotation effect. The copper oxide minerals which can be treated by the vulcanization method, mainly copper carbonates, such as malachite, azurite, etc.; can also be used for flotation of copper ore, and the cyanite is vulcanized without special treatment in advance. The effect is very poor and can't even be vulcanized.
In recent years, sodium polysulfide has been used as a vulcanizing agent at home and abroad to vulcanize flotation malachite and chrysocolla. For example, Professor S. Chander in the United States uses sodium tetrasulfide and sodium sulfide to vulcanize flotation malachite, and uses various testing methods to demonstrate from different sides that sodium tetrasulfide not only reduces the amount of xanthate compared with sodium sulfide, but also The flotation index has been greatly improved. In 1993, the former Soviet Union Л·A·Tлa3yHOB used sodium sulfide, sodium disulfide, sodium tetrasulfide and sodium pentasulfide to vulcanize flotation of cyanite. The results showed that the vulcanization effect of sodium sulfite in the above several vulcanizing agents. Preferably, the vulcanized cetacean flotation index is best.
A copper oxide ore is subjected to conventional vulcanization flotation. The main feature of the deposit is that the copper ore reserves are large and the ore grade is low. The oxidation rate is high, the content of combined copper oxide is high, and the copper mineral is extremely fine-grained, belonging to the refractory copper oxide ore.
The ore beneficiation plant process to oxide minerals, accounting for about 60% to 80% of the copper minerals, copper oxide was again mainly malachite, chrysocolla followed. Copper oxide was disseminated aryl fine particles, mostly "chromosome", with a few brown iron ore symbiotic. Copper sulphide minerals are mainly porphyrites, followed by brilliite and blue copper, and less chalcopyrite. The gangue minerals are mainly dolomite, followed by quartz , and there are still a small amount of limonite, tourmaline and pyrite.
The plant adopts the stage grinding stage flotation process, as shown in Figure 1. Its production indicators are: raw ore containing 0.76% copper, the final copper concentrate containing 17.66% copper, the recovery rate is 75.04%. 
Figure 1 Vulcanization flotation process of a copper oxide ore
In the process of vulcanization flotation, in order to strengthen the vulcanization effect, sodium sulfide should be added in stages according to a certain proportion and amount to achieve the best vulcanization effect. Production practice shows that different ores have different optimal sodium sulfide dosage ranges, and when properly controlled, the foam mineralization is good, and the recovery rate can be increased by 2% to 3%. The optimum dosage of sodium sulfide is: oxidation rate below 45%, dosage not exceeding 1700g/t; oxidation rate 55% to 65%, dosage 2200g/t; oxidation rate above 75%, dosage not exceeding 3500g/t. And should be used in conjunction adjuster stick ethylenediamine phosphate and ammonium sulfate, to enhance the vulcanization process.
(2) Hydrothermal vulcanization flotation method
This method is actually a development of the conventional vulcanization flotation method, which essentially chemically reacts sulfur with copper oxide mineral under hot pressing conditions to form a stable and easily selected artificial copper sulfide mineral, and in warm water. It is recovered by flotation of copper sulfide, which is characterized by strengthening the pretreatment-pre-vulcanization process of the ore and performing flotation in warm water.
The principle of this method is: adding the slurry of the vulcanizing agent, when the temperature rises to a certain extent, the elemental sulfur generates S 4 2 - ions into the solution due to its own redox reaction; when the 2-ion and the copper oxide mineral meet A chemical reaction occurs to form a copper sulfide mineral. The redox reaction formula of elemental sulfur in aqueous solution is:
4S+4H 2 O→3S 2 - +SO 4 2 - +8H+
The vulcanization reaction first occurs on the surface of the copper oxide mineral and gradually penetrates into the interior of the mineral particles from the surface and inside. For example, the vulcanization reaction formula of malachite is:
Cu(OH) 2 ·CuCO 3 +8S+2H 2 O→6CuS+2H 2 SO 4 +3H 2 CO 3
During the hot water vulcanization process, the vulcanization temperature, ore size, sulfur content and vulcanization time have different effects on the copper oxide transfer.
Hydrothermal vulcanization flotation of a refractory copper oxide ore. The ore is firstly crushed and ground, and after reaching a predetermined particle size, elemental sulfur is added, and the copper oxide mineral is forcibly vulcanized under a certain temperature and pressure. After completion of vulcanization, heat the slurry under reduced pressure, adding flotation agent, in warm water - and copper sulfide flotation synthetic natural sulfur and copper. The principle process is shown in Figure 2.
The conditions of hydrothermal vulcanization are: vulcanization temperature of 180 ° C, ore particle size of 93% to 95% (-200 mesh), sulfur amount of 1.4 to 1.5 times the theoretical amount, and vulcanization time of 4 h. The hydrothermal vulcanization flotation is compared with the small test results of conventional vulcanization flotation, see Table 1. It can be seen from Table 1 that the concentrate grade and recovery rate of hydrothermal sulfide flotation copper are 7.88% and 13.80% higher than conventional sulfide flotation, respectively.
Table 1 Small test results of hydrothermal vulcanization flotation
The biggest problem in this method is high temperature requirement, high fuel consumption and long curing time. Therefore, lowering the vulcanization temperature and shortening the vulcanization time are prerequisites for the promotion and application of this method in production. The Chinese Academy of Sciences has made significant progress in this area. They use phase transfer catalysis to promote the disproportionation of elemental sulfur, which greatly reduces the vulcanization temperature of hydrothermal vulcanization and shortens the vulcanization time.
Second, fatty acid flotation
Fatty acid floatation is also known as direct flotation. When using fatty acids and their soaps as collectors for flotation, it is usually necessary to add gangue inhibitor water glass, phosphate and slurry adjuster sodium carbonate.
Fatty acids and their soaps can well float malachite and azurite. The test results of fatty acid flotation of malachite with different hydrocarbon chains show that the fatty acid has a strong ability to capture malachite as long as the hydrocarbon chain is long enough. The stronger the collection ability is within a certain range, the less the amount of the agent is used, and the mixed saturated or unsaturated carboxylic acid of C10 to C20 is used in the production practice. This method only applies to copper oxide carbonate gangue not when the gangue contains large amounts of iron, manganese minerals, the index will be deteriorated; additional fatty acid sludge also fail, so little progress in this method.
In foreign countries, the concentrating plant that used this method in the past, except for a few, most of the plants are supplemented with sodium sulfide and xanthate or directly changed to sulfide flotation. For example, the Nchangga concentrator in Zambia uses a vulcanization method and a fatty acid method to float copper oxide ore. The treated ore is a sulfide-oxidized mixed ore containing carbonate gangue. The main copper minerals are chalcopyrite, malachite, azurite and azurite, and a small amount of chalcopyrite and porphyrite. A part of the copper oxide mineral and copper sulfide which have been vulcanized during flotation are floated with xanthate, and the flotation tailings are used to float the residual copper oxide ore with fatty acid (palmitic acid). The ore contains 4.7% copper and the concentrate contains 50% to 55% copper. The pharmaceutical system is: lime 500g / t (pH = 9 ~ 9.5), sodium sulfide 1000g / t, palmitic acid 400g / t, cresol 10g / t, fuel oil 75g / t.
Third, the amine flotation method
With an amine as collector flotation, flotation is a common method of non-ferrous metal oxide ore (copper, lead, zinc oxide ore), suitable for processing malachite, azurite, copper chloride and the like.
Amines are effective collectors for copper oxide ore, but their selectivity is poor and they have a catching effect on many gangues. Therefore, the amine method is often delimed. However, for muddy copper oxide ore, pre-desilting will cause copper loss, so the key to the amine method is how to find effective inhibitors of gangue. Effective inhibitors of current gangue are: seaweed powder, lignosulfonate or cellulose lignosulfonate, polyacrylic acid, and the like.
Flotation of malachite with an amine requires a higher pH than xanthate. The test results show that the pH value is between 10 and 11, and the vulcanization of sodium sulfide is the best. In addition, the use of amines as collectors is faster than flotation.
The amine collectors currently used are laurylamine and cocoamine, or a mixture of fatty amines and amines having 10 to 14 carbons with two NH2 groups. When used, adding diesel as an emulsion can greatly improve the flotation efficiency.
Fourth, emulsion flotation
The copper oxide mineral is first vulcanized, then a copper complexing agent is added to form a stable oleophilic mineral surface, and then covered with a neutral oil emulsion on the surface of the mineral, resulting in a highly hydrophobic floatable state, thus firmly adhering The bubble floats up.
The essence of the emulsion flotation method includes three aspects: (1) using a selective organic compound copper complexing agent to form a stable slightly hydrophobic and very lipophilic film on the surface of the mineral. Copper complexing agents are: benzotriazole toluene triazole, mercaptobenzothiazole, diphenylguanidine and the like. (2) adding a non-polar oil emulsion to increase the adhesion of bubbles and mineral, a non-polar oil emulsifier available gasoline, kerosene and diesel. (3) Use of selective gangue inhibitors such as acrylic acid polymers and sodium silicate.
5. Chelating agent-neutral oil flotation method
For the refractory copper oxide ore (such as chrysocolla), it is recovered by several flotation methods mentioned above, the selectivity is not strong, and the recovery rate is not high. In order to effectively recover the refractory copper oxide ore. A highly selective collector must be sought, and a flotation process with a chelating agent plus a neutral oil has been proposed.
The method refers to the use of a chelating agent and a neutral oil to form a collector. The results show that the use of a chelating agent as a collector not only achieves high selectivity and capture, but also ensures high sorting index and reduced consumption of the agent, while the chelating agent also has selective inhibition. However, due to the high cost of the chelating agent, the promotion and application in production are limited. Currently, chelating agents such as octyl-substituted basic dyes malachite green, potassium octyloxycitrate, benzotriazole and neutral oil emulsifiers, N-substituted imine diacetates, polyamines and organics are used. a condensate of a halide or the like.
Several flotation methods for copper oxide ore have been described above. In addition, the use of an external energy field can also significantly improve the flotation process of copper oxide ore. There are many reports at home and abroad, such as using r-ray irradiation to improve the floatability of minerals, electrochemical treatment of slurry, electric field treatment of chemicals, treatment of floating water by magnetic field, etc., can be played to varying degrees. Improve the flotation process, reduce the consumption of pharmaceuticals and other aspects.
There are many treatment methods for copper oxide at present, but the flotation method, especially the recovery of xanthate after vulcanization, is still the main method for treating copper oxide ore.
Figure 2 Flow chart of hydrothermal vulcanization flotation principle of a copper oxide ore
Mineral processing method
Raw ore grade /%
Concentrate grade /%
Tailings grade /%
Recovery rate/%
Conventional sulfide flotation
Hydrothermal vulcanization flotation
0.602
0.595
18.97
10.09
0.081
0.167
86.89
73.09