Mining Industry

 from Diphex Chemical Safety

The mining industry is the exploration, exploitation and refining of ores to extract minerals with commercial value. This can be the extraction of:

  • metal ores eg gold, silver, zinc,
  • non-metallic ores eg phosphate, lime
  • precious stones eg diamonds, rubies, opals

Many of the processes use chemicals to extract the valuable components from the agglomerations.

EXPLORATION

Prior to developing a mine works will be carried out to evaluate the quality of the ore and the most appropriate place to commence the mining. Rock samples may be digested with chemicals during testing prior to analysis. These digesters can include acids such as Hydrochloric, Nitric or Perchloric, alkalis such as Sodium Hydroxide, Sodium Carbonate or Sodium Peroxide.

It should also be noted that Hydrofluoric Acid is often used due to its ability to dissolve most oxides and silicates. Hydrofluoric Acid carries both a corrosive and toxic risk and specific first aid protocols should be put in place to deal with both the H+ ion and the F- ion. Please review the information provided on our Hexafluorine® page and our Hydrofluoric Acid booklet is available to download from this section too.

LEACHING PROCESS

This process allows the soluble metallic compounds to be removed from the ore using a selective solvent. Different ores require different solvents  however it is  is often Sulphuric Acid or Sodium Cyanide.

Other chemicals are often added during the procedures to control the process eg the addition of alkalis during gold extraction to prevent the cyanide ions used for the leaching process from turning to toxic cyanide gases.

The use of Sulphuric Acid in leaching processes at large mines can exceed 15,000 tonnes per day and hence the site may have its own Sulphuric Acid production plant.

Alumina is extracted from ore using hot Sodium Hydroxide

CLARIFICATION

This involves the separation of solids from the saturated liquor- often using chemical flocculants such as lime, soda ash, caustic soda.

EFFLUENT

These extraction processes result in high levels of liquid waste requireing on site treatment. As seen in our study on this sector (see Market Sectors - Water Treatment) this requires a number of chemical processes often using Sodium Hydroxide and Sulphuric Acid.