Brief Introduction of Dithiophosphate

Dithiophosphate is a collector used in the flotation process. It can enhance the hydrophobicity of the mineral surface make the mineral easy to adsorb on the foam, thus improving the flotability of the mineral. In this way, the mineral can be captured by the foam and enriched.

1. Introduction of Dithiophosphate

There are many kinds of dithiophosphates, most of them are dark green oily liquids, slightly soluble in water, corrosive, and will decompose when exposed to heat. The chemical name of dithiophosphate is dihydrocarbyl dithiophosphates. The dithiophosphate can be regarded as a derivative in which two oxygens are replaced by sulfur in the dihydrogen phosphate, and is classified into two major categories of dialkyldithiophosphate and dialkylmonothiophosphate.

Dithiophosphate was first used in 1925, and it is widely used in the flotation of sulfide minerals, second only to xanthate. In addition to its collecting properties, it also has foaming properties.

2. Nature of Dithiophosphate

The nature of dithiophosphate is relatively stable and difficult to decompose. After being oxidized, the dithiophosphate can become “re-dithiophosphate”, and this “re-dithiophosphate” is also a collector of sulfide ore.

The selectivity of dithiophosphate is relatively good, and the ability to collect pyrite is poor. With this property, dithiophosphate can be used for flotation of other sulfide ore containing pyrite. For example, using dithiophosphate as collector of priority flotation in the copper and lead-zinc sulfide ore contains high iron sulfide can obtain high quality concentrates. At the same time, there are many kinds of dithiophosphates that have good collecting performance for gold. Moreover, because the dithiophosphate usually dissolves a small amount of sulfuric acid such as hydrogen sulfide or sodium sulfide, it is also suitable for flotation of slightly oxidized sulfide ore.

The acid dithiophosphate is insoluble in water, but is soluble in an organic solvent such as aniline. In addition, the ammonium and sodium salts of the dithiophosphate can be dissolved in water to form a turbid liquid which can be added to the flotation process directly.

3. Classification of Dithiophosphate

There are many kinds of dithiophosphates, which can be mainly divided into cresol dithiophosphate and ammonium aibutyl dithiophosphate. And cresol dithiophosphate is divided into three kinds according to the amount of phosphorus pentoxide added in the manufacture of ingredients: dithiophosphate 15, dithiophosphate 25 and dithiophosphate 31, the most commonly used is dithiophosphate 25.

1) Dithiophosphate 25

Dithiophosphate 25 has both collecting and foaming properties. It is an effective collector for copper, lead and silver sulfide ore and activated zinc sulfide ore. It is commonly used in the priority flotation separation of lead ore and zinc ore. In the alkaline medium, the dithiophosphate 25 has weak collecting effect to pyrite and other sulfide minerals, and has certain selectivity. However, in neutral or acidic medium, dithiophosphate 25 is the strong collector of all sulfide minerals without selecting property. In addition, under certain conditions, dithiophosphate 25 also has a certain collecting effect on heavy metal oxidized ore.

Dithiophosphate 25 can only be slightly soluble in water, so it must be added to the ball mill or the adjustment tank in its original form.

2) Ammonium aibutyl dithiophosphate

Ammonium Aibutyl Dithiophosphate is white powdery solid, soluble in water, odorless, non-irritating odor, deliquescent in the air. The appearance of ammonium aibutyl dithiophosphate is white to gray and sometimes slightly pink, and the particle is from fine grains to powder.

The ammonium aibutyl dithiophosphate has stable flotation stability and good selectivity, and is an excellent collector and foaming agent for non-ferrous metal ore. It has special separating effect on copper, lead, silver and activated zinc sulfide ore and hard-to-separate polymetallic ore. It can also be used for flotation of nickel and antimony sulfide ore, especially for hard-to-separate nickel sulfide ore, the sulfide-oxide mixed nickel ore and the middlings of sulfide ore and gangue. In the weakly alkaline ore pulp, ammonium aibutyl dithiophosphate has a relatively poor collecting ability to the pyrite and pyrrhotite ore, while has a stronger ability to collect galena.

According to the research, the use of ammonium aibutyl dithiophosphate is also beneficial to the recovery of platinum, gold and silver. When using ammonium aibutyl dithiophosphate instead of xanthate in the flotation process of gold, the gold recovery rate and concentrate grade will be greatly improved.

In summary, the dithiophosphate is mainly suitable for the flotation of sulfide minerals. Dithiophosphate not only has good collecting property, but also has certain selectivity. Besides, dithiophosphate has foaming property, thus can reduce the amount of foaming agent when used.

In addition, besides having good flotation performance to sulfide ore, dithiophosphate 25 and ammonium aibutyl dithiophosphate have some other effects. For example, ammonium aibutyl dithiophosphate is more suitable for the flotation of platinum, gold and other precious metals and some hard-to-separate polymetallic ore, while the dithiophosphate 25 has a certain collecting effect on heavy metal oxide ore.

Dithiophosphate is widely used in flotation process, but not all of ores can be separated by dithiophosphate. In actual production, the staff of flotation plant should combine the actual conditions, the results of the ore processing test, the recommendations of the technical staff and the content above to choose a proper flotation reagent to get the best flotation effect.