What is a Flotation Collector?
A flotation collector is a type of flotation reagent that alters the hydrophobicity of mineral surfaces, enabling floating mineral particles to adhere to air bubbles.
It is one of the most important classes of flotation reagents and possesses two fundamental properties:
- Selective adsorption on mineral surfaces
- Ability to increase the hydrophobicity of mineral surfaces, enhancing the floatability of minerals
Among collectors, black drugs (thiophosphate) are especially significant.
What is Thiophosphate (Black Drug)?
Thiophosphate, commonly referred to as “black drug,” is an organic derivative of phosphoric acid. In thiophosphate:
- Two oxygen atoms in phosphoric acid are replaced by sulfur atoms.
- Two hydrogen atoms are replaced by organic groups.
Its general formula can be represented as:
(RO)₂PSSH (Me)
In China, the most commonly used black drugs include:
- Phenol-based black drug （Dithiophosphate 25）
- Dibutyl ammonium black drug （Dithiophosphate BA）
- Aniline black drug （Amino-dithiophosphate）
Types of Black Drugs
- Phenol-Based Black Drug （Dithiophosphate 25）
- Appearance: Dark green oily liquid
- Characteristics:
- Slightly soluble in water
- Density: 1.2 g/cm³
- Has an unpleasant odor of hydrogen sulfide
- Can cause skin burns
- Contains phenol, with foaming properties, and is flammable
- Toxicity: Lower than yellow drugs
- Dibutyl Ammonium Black Drug （Dithiophosphate BA）
- Appearance: White or gray powder
- Characteristics:
- Highly soluble in water
- Prone to deliquescence and turns black upon exposure to air
- Has some foaming properties
- Can cause skin corrosion
- Aniline Black Drug
- Appearance: White powder
- Characteristics:
- Insoluble in water
- Soluble in alcohol and dilute alkaline solutions (e.g., sodium carbonate or sodium hydroxide)
- Poor stability to light and heat
- Has an odor and is prone to deliquescence
Properties of Black Drugs
Compared to yellow drugs, black drugs have the following characteristics:
- Greater stability
- Less prone to decomposition in acidic pulp
- Lower toxicity
Black drugs form weaker bonds with the sulfide minerals on account of their central phosphorus and sulfur atoms, resulting in:
- Reduced collecting power compared to yellow drugs
- Better selectivity in flotation
Application and Storage of Black Drugs
Storage Tips:
- Keep in sealed containers to avoid contact with moisture and air
- Store in a cool, dry, well-ventilated place
- Avoid long-term exposure to light or heat
Application Methods:
- Phenol-Based Black Drug:
- Used as is, typically added directly to ball mills due to its low solubility in water
- Dibutyl Ammonium Black Drug:
- Dissolved in water to prepare a 5% solution before use
- Solution can be prepared daily or per shift
- Aniline Black Drug:
- Dissolved in 1% sodium carbonate solution
- Prepared as a 5% solution for application
