The heat treatment can decompose, oxidize or evaporate the collector hydrophobic film adsorbed on the mineral surface. Non- molybdenum sulfide minerals ( copper , iron , lead sulfide) can also be easily oxidized than molybdenum ore. After heat treatment, molybdenite is not oxidized and floatability changes little; non-molybdenum sulfide surface It has been oxidized and is naturally inhibited. These can increase the difference in floatability between molybdenite and non-molybdenum sulfide impurities, and facilitate copper-molybdenum separation.
There are two heat treatment processes: steam heating slurry and low temperature baking filter. The heat treatment complicates the copper-molybdenum separation and increases the fuel cost. However, the heat treatment makes the copper-molybdenum sorting effect significantly improved. Therefore, about 40% of the world's major copper-molybdenum plants use a heat treatment process for copper-molybdenum sorting.
Steam heated pulp, the temperature should be controlled below the boiling point and close to the boiling point, usually 85 ~ 96 ° C. There are three heating methods: the steam is directly heated by the slurry; the steam is indirectly heated by the heat exchanger; the steam is introduced into the autoclave, and the slurry is directly pressurized and heated.
Hash former Soviet Barr, Lake Alma as copper - molybdenum beneficiation plant using direct steam heating process: Cu - Mo sulfide mixed concentrate was slurried in advance, during the sorting, the live steam into the flotation cell, It is used to heat the slurry and replace the air as a bubble medium. The pulp is usually warmed to 60 ° C ± 5 ° C. Production practice has confirmed that steam heating of the slurry can enhance the desorption of sodium sulfide on the mineral surface collector, and also reduce the amount of dissolved oxygen in the slurry, thereby reducing the oxidation loss of sodium sulfide. After steam heating in production, the consumption of sodium sulfide is reduced by 85%~91%, the consumption of water glass is reduced by 50%, and the quality of molybdenum concentrate and the recovery rate of molybdenum are also significantly improved.
Migill's copper-molybdenum blend contains 19% copper and 0.15% molybdenum. After the mixed concentrate was concentrated to 50% solids, it was heated by steaming, and the slurry was warmed to 87.8 ° C and cooked for 90 min. The heat-treated pulp was re-pulped and adjusted to 32.2 ° C and 20% solids, followed by arsenic Knox copper molybdenum. The West Yalita steamed into the mixed concentrate concentrated to 52% solids. When the slurry was steamed to 82.2 ° C and heated for 15 min, it was further refined and copper-molybdenated. Chino concentrates the concentrate to 40% to 50% solids, heats it with steam, heats the slurry to 85 ° C, and then performs copper-molybdenum sorting.
Miami, Esperanza, Inspiresin will concentrate the concentrated concentrate into the autoclave and then steam, and carry out the pressure cooking in the kettle. Chuquikama has a cooking pressure of 0.68 MPa, and the pulp is heated to 85 ° C. After cooking for a period of time, it is discharged from the autoclave, and the steamed pulp is cooled. After the slurry is added, sodium ferrocyanide (400 g/t) is added. Copper-suppressed molybdenum.
Plants such as Baghdad circulate steam into the heat exchanger. After the copper-molybdenum mixed concentrate is concentrated to 50% solids, it is firstly pulverized with sulfuric acid (up to pH 5.5), and then heated to a temperature of 96 ° C by heat exchanger to cook for about 1 hour. The slurry after heat treatment is slurried and cooled. After 38 ° C, Knox's agent was added for copper-molybdenum sorting. Molybdenum selection operations must also add sodium cyanide or sodium sulfide to further inhibit copper minerals. The flotation molybdenum concentrate contains 55% molybdenum and 0.5% copper.
Before steaming, if the content of copper oxide in the mixed concentrate is high, it is often necessary to add lime and then steam. It can destroy the mineral surface collector, increase the pH value of the slurry and reduce the consumption of sodium sulfide. Moranxi used the lime steaming process.
The steam heating temperature is low, it is difficult to remove the adsorbed agent on the mineral surface, especially after the molybdenum molybdenum floating copper process has been used, in order to completely remove the agent to activate the molybdenite, the roasting process is often used. [next]
The roasting process usually consists of: filtration, roasting, slurrying, and sorting. Sometimes it is necessary to increase the regrind operation before mixing.
When roasting, it is necessary to destroy the surface of the mineral, and also to oxidize the surface of the sulfide mineral of copper and iron without oxidizing the surface of the molybdenite. This requires strict control of the calcination temperature and time.
Japan Matsubara's research found that the mixing concentrate temperature should not be less than 275 ° C; roasting for 1 h, copper - molybdenum minerals can be well separated, see Figure 1 ~ Figure 3.
Fig.1 Effect of calcination temperature on Cu-Mo sorting
Figure 2 Effect of roasting time on Cu-Mo sorting
Fig. 3 Separation effect of roasting on copper and molybdenum (according to Japanese Matsubara wide data)
U.S. silver bell Cu - Mo concentrator Cu - Mo sorting through three stages: a floating suppressing copper molybdenum; molybdenum roasting products, rougher molybdenum (Mo floating suppressing copper); suppression sodium cyanide copper, molybdenum selection.
Silver Bell first added dextrin to molybdenum float copper to the mixed concentrate, and the molybdenum product (in-tank product) contained molybdenum was still very low. (20.0% copper, 2.0% MoS 2 ). The molybdenum product is first filtered, filtered and entered into a five-layer multi-hearth furnace to control the temperature to be calcined at 260-310 ° C for 2 h. The roasting product has removed all of the agents including dextrin. Calcined products must be added with lime to prevent the pulp from being acidic and activate copper and iron sulfides. The amount of lime can be as long as the pH is about 7. After the slurry is adjusted, only the hydrocarbon oil and the foaming agent are added, and the crude molybdenum concentrate containing MoS 2 15.2% and copper 15% can be obtained.
In the process of selection, the coarse concentrate of molybdenum is added with sodium cyanide to inhibit copper minerals, and finally obtains MoS 2 88% and copper 0.5% qualified molybdenum concentrate.
Bingham, Chino, Pima, etc. also have low-temperature roasting process, but these plants are used to remove the easy-floating gangue. After roasting, it is selected in an acidic medium to inhibit molybdenite, flotation talc , mica, etc. Easy to float gangue minerals.
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