Gold Recovery Flotation

Gold Recovery process

Much, but not all of the free gold was floated with the copper concentrates. To recover the rest, the pulp was passed over woolen blankets (before the pyrite was floated) where the gold would settle out. The little silver that was recovered at Britannia was also taken out this way.

Gold Recovery Flotation

The area of the blankets was around 20’ x 40’ and was on a very shallow grade. Every 8 hours they were mechanically rolled over and washed to remove the gold.

Other Britannia Facts

• Copper sulphate was used in the extraction of the zinc sulphide
• The Lead Plant was built in 1951 to separate the lead sulphide from the copper sulphide , partly through centrifugal separation in cyclones and partly through flotation
• Soda ash was used until 1930 as a modifying agent to preciptitate soluble salts (sulphates). But the quantity of salts in the ore increased over this decade meaning that the quantity of soda ash being used increased too. It became too expensive, so the flotation time was lengthened instead. These salts are harmful to flotation as they react with the ore preventing them from being water repellent
•  Aeroflot 25 was a collector agent also used in small quantities from 1928 – ?

Glossary

Activate – See Collect

• Collect/collector – Chemical reagent used to make the ore water-repellent and help it stick to the bubbles
• Conditioning – Preparing the pulp by adding reagents and giving time for the chemical reactions to work
• Depress/depressant – Chemical reagent used to stop a mineral from floating
• Emulsify – Being able to mix two liquids that don’t normally mix well, e.g. oil and water
• Flocculent – Chemical reagent used to help the valuable mineral particles stick together
• Frother/frothing agent – Chemical reagent added to the pulp to make stable bubbles
• Gangue – Gangue (pronounced ‘gang’) is the waste rock/minerals produced from flotation Heteropolar Molecules that have both polar and non-polar parts, i.e a water-repellent and water-soluble part
• Hydrophilic – Molecules that are water-soluble, i.e. at a molecular level they are pulled towards water molecules and bind together
• Hydrophobic – Molecules that are water-repellent, i.e. at a molecular level they are pushed away from water
• Pulp – The ore and water mix going through the flotation process
• Rougher cell – The flotation cells where the bulk of the gangue is removed from the concentrate

Mill Timeline – Key Dates

• 1905 – Mill 1 opens
• 1912 – First copper producer in North America to install a flotation unit as part of regular processing (Mineral Separation type)
• 1913 – First copper producer in Canada to use selective flotation
• 1916 – Power and water shortages meant Mill couldn’t keep up with supply. Stockpile locations built above Mill site
• 1916 – Mill 2 fully operational
• 1919 – Mill 1 demolished
• 1921 – Mill 2 burnt down
• 1922/3 – Mill 3 built
• 1924 – Gold recovery begun in Mill 3 (though had been being extracted in earlier mill operations); Pyrite recovery begun (in May) in Mill 3 due to opening of market ; Rail slugs used for grinding; ball-making machine installed at Beach
• 1930 – Production reached a peak of 7100 tons per day, but averaging over 6000 tons per day over the year 1935 Zinc production had begun
• 1936 – Britannia ranked as lowest copper producer in world due to mining operation efficiencies (will have been contributed to by milling operations)
• 1938 – Production had declined during the Depression, but regained to around 6000 tons per day
• 1939/45 – During (but not necessarily throughout) World War II, production rose to record 7200 tons ore per day, due to high copper prices
• 1952 – Production reduced to 3000 tons per day (after several ball mills taken out of operation)
• 1956 – Rod mills were replacing ball mills and roll mills as they were more efficient
• 1958 – Primary crushing underground becomes cost prohibitive due to scale of mine; jaw crusher installed in Mill to process ore not crushed underground

Categories: Beneficiation Plant Tags: Britannia , copper , flotation process , gold recovery , mill , water