9. Describe methods of waste-free processing of molybdenum.

1. Molibdenum from flue dust smelters.

This process is designed X. Castagna. The circuit is shown in Figure 1.

T he scheme of allocation of molybdenum from spent catalysts:

1-Na2CO3 solution;

2-impregnation; 3-sintering;

4 hot water; 5-dissolution;

6-conc. HNO3; 7-neutralization;

8-advocacy; 9-deposition;

10-1% solution HNO3;

11-filtering and washing;

12-dryer; 13-dry molybdic acid; 14-residues; 15-remote-solid;

16-wash.

1) The firing of the spent catalyst (8% Mo, 1.5% S and about 2% Co) at a temperature of about 500 ° C, the volatiles were removed, carbon, sulfur.

2) Treatment of an aqueous solution (400 g/l Na2C03) at 70°C.

3) Heating of a propane torch to a temperature 650-750°C for 1 hour.

4) Cool to 70-80 ° C in a refrigerator (about 95% Mb as sodium molybdate).

5) dissolution, flushing (6 stages) sodium molybdate. The yield of the washing stage - 97%.

6) Deposition of molybdic acid.

7) separating the precipitate, washing, drying. The yield of Mo in the form of molybdic acid ~ 85%.

2.Molibden waste manufacturing process of tungsten light bulbs.

The process developed AD Kulkarni. It provides for allocation of molybdenum from spent solutions of sulfuric and nitric acid by the addition of ammonium hydroxide until a pH value of 1.5-3, preferably 2-3. The solution was then stirred while heating to a temperature of 95 ° C until all of the dissolved molybdenum separates as not to precipitate ammonium molybdate complex. The precipitate was separated from the solution.

T he scheme of allocation of molybdenum from spent acid solutions, resulting in the production of tungsten filaments:

1 - solution 40-75 g/l molybdenum 15H acid; 2 - ammonia; 3 - set pH = 2-3 and stirred for 10 hours at a temperature of 70-80 ° C; 4 - wash water; 5 - decanting; 6 - flushing; 7 - the mother liquor; 8 - the filter; 9 - high purity product acid.

10. Describe the main problems flotation of minerals and loss of useful components in the flotation mineral processing

Flotation - the most universal and progressive method of enrichment - is one of the basic processes in the processing of ores of rare metals.

The main technological parameters of flotation - a degree of extraction of metal in concentrate and concentrate grade, determined the percentage of it recoverable metal impurities.

Flotation enrich only small classes (0.5 - 0 mm). This method is based on the difference in the wettability of the mineral surfaces, which are separated. The greater the difference in wettability, the more likely that some particles will stick to the surface of the bubble and float it up, and the other into effect their highly hydrophilic surface will remain suspended in the slurry. The difference in wettability can be increased or reduced by using special reagents that are added to the pulp before or during enrichment.

Flotation - it is a complex process that depends on many factors. But thin particles behave very differently than larger grains. For flotation such particles also hardly enrichment. Fine grains not only take the reagent because of its large specific surface, the probability of them transition in the froth product essentially reduced, since due to the hydrodynamic processes in the pulp, fine particles of a substance, usually do not settle on bubbles with air, they simply bypass them rushing to the flow of pulp and lost to waste. It is very difficult to operate such a process, even the use of strong reagents does not solve the problem of retaining fine particles to the air bubbles.