Black medicine is second only to xanthate, and it is widely used as a sulfide mineral collector . Aerofloat dihydrocarbyl dithiophosphate is a phosphate, wherein the hydrocarbon used is a cresol group or an alkoxy group. At present, the black medicine produced has two kinds of cresol black medicine and butyl ammonium black medicine. Its structural formula (see picture ) is:
R — O | S | |
  \ | ∥ | |
P | ||
/ | \ | |
R — O | SMe (H or NH 4 ) | |
C 6 H 4 CH 3 O | S | |
\ | ∥ | |
P — S — Na ( cresol black medicine ) | ||
/ | ||
C 6 H 4 CH 3 O | ||
C 4 H 9 O | S | |
\ | ∥ | |
P — S — NH 4 (butylammonium black) | ||
/ | ||
C 4 H 9 O | ||
Black medicine structure diagram
   It is composed of an alcohol or phenol with phosphorus pentasulfide reaction is, different phenols or alcohols can be obtained a wide variety of black powder. Its reaction formula is:
4ROH+P 2 S 5 → 2 ( RO ) 2 PSSH+H 2 S
The acid product is an oily black liquid which can be made into a water or solid product when neutralized to a sodium or ammonium salt.
The most common practice in mineral processing practice is cresol black medicine. The cresol black medicine has different proportions according to the action of phosphorus pentasulfide and cresylic acid, and is divided into 15th , 25th , 31st and so on. For example, the 15th black medicine is the product of the action of cresol and its 15% by weight of phosphorus pentasulfide.
The cresol black medicine is a dark green oily liquid, slightly soluble in water, has a specific gravity of 1.1 , has an unpleasant odor, is corrosive, and can burn the skin. Since it contains unreacted cresol, it has foaming property. It is often added to the ball mill during use.
Black drug is effective sulphide ore collector, which collector capacity than xanthate weak but selective, the same metal dihydrocarbyl dithiophosphate ion solubility product than those of the corresponding xanthate ion large .
Black medicine is also a weak electrolyte that dissociates in water:
( RO ) 2 PS S ≒ ( RO ) 2 PSS - + H +
     However, it is more stable than xanthate. In acidic pulp, it is not as easy to decompose as yellow medicine. Aerofloat difficult oxide, black powder epigenetic pairs, have the Cu 2+, Fe 3+, or pyrite, Hui copper ore there can also be a double oxide black powder:
2 ( RO ) 2 PSS — 2e →( RO ) 2 PSS-SSP ( OR ) 2
     Double black medicine is also a non-ionic collector which is hardly soluble in water. Most of them are oily substances. They are stable in nature and can be used as collectors for sulfide ore. They are also suitable for flotation of deposited metals.
Black medicine is somewhat toxic, its selectivity is better than that of xanthate, and it is not easy to decompose in acidic pulp. When it is necessary to float in an acidic slurry, black medicine is sometimes used.
The butylammonium black drug is dibutylammonium dithiophosphate ( C 4 H 9 ) 2 PSSNH 4 , which is a white fine-grained crystalline powder, slightly odorous , easily soluble in water, and blackened after deliquescence. Under normal circumstances, it is not easy to deteriorate, is stable, has foaming, and is non-corrosive. Suitable for flotation of copper, lead , zinc , nickel and other sulfide ore. The weak alkaline pulp has weaker ability to capture pyrite and pyrrhotite, and the lead in the other is more capable of collecting. Because the black medicine has foaming performance, the dosage should not be too large when used, generally 25~
In addition, there is an amine black drug, which has a structure similar to that of black medicine, and has the formula ( RNH) 2 PSSH . It is also a collector for sulfide ore. Commonly used in the industry are cyclohexylamine and aniline black medicine, which are all obtained by reacting corresponding raw materials with phosphorus pentasulfide. It is a white powder with hydrogen sulfide odor, insoluble in water, soluble in alcohol and dilute alkali solution. Formulated with 1% 0.5% Na 2 CO 3 was added when used. Amine black medicine has poor stability to light and heat and is prone to deterioration.
Amine black medicine has strong ability to capture lead sulfide ore, has good selectivity, and the foam is not sticky, but the dosage is slightly larger, generally 200~
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