Platinum is a rare metal found in the earth’s crust at 0.005ppm. According to Louis XV of France, platinum is the only metal meant for a king. It is found in iron, nickel and copper ores with other native deposits. Platinum is a noble metal that can withstand corrosion at high temperatures and is least reactive. It is rated 3.5 on the Moh’s scale of hardness, has a melting point of 1768.3 degrees Celsius, a boiling point of 3825 degrees Celsius, the density of 21.45g per cubic meter and molar heat capacity of 25.86J. Platinum is lustrous, ductile and malleable. It has stable electrical properties.
This metal oxidizes at 500 degrees Celsius to form Platinum oxide which can be thermally removed. It also reacts with fluorine at 500 degrees celsius to form platinum tetrafluoride. Platinum does not dissolve in hydrochloric acid or nitric acid but is soluble in a combination of the two (aqua regia) at high temperatures to form chloroplatinic acid. It is attacked by iodine, bromine, chlorine, and sulfur. Platinum has a high affinity for Sulphur which is mostly found in iron ores.
Platinum group ores are treated in primary and secondary crushers. Ball/Rod mills are used in the tertiary stages of comminution. The milled ore is treated in gravity concentrators. In froth floatation, xanthate and dithiophosphate are the collectors used at a pH of 7.5-9. Oxygen is also used in the froth floatation process. The concentrate is dried and rectangular-six-in-line or circular three-electrode furnaces are used to separate sulphides and silicates at 900-1500 degrees Celsius. Air is blown through the furnace to remove iron and Sulphur. Chemical and electrolytic methods are manipulated to remove nickel, cobalt, and copper. Aqua regia is then used to dissolve platinum metal from the concentrate by creating chloroplatinic acid. Finally, ammonium chloride is used to change chloroplatinic acid to ammonium hexachloroplatinate which is heated to produce pure platinum metal.
This metal is used in jewelry, electrical appliances, chemical production, petroleum refining, and vehicle emissions control. Platinum is also used in medicine, biomedicine, glassmaking equipment, anticancer drugs, oxygen sensors, turbine engines, spark plugs, electrodes and even in investment. It is used as a catalyst in the ignition of hydrogen. In the petroleum industry, platinum is used to run naphthas into octane gasoline which becomes rich in aromatic compounds. It strongly catalyses the decomposition of hydrogen peroxide into water and oxygen hence, It is used in fuel cells as a catalyst for the reduction of oxygen. In investment, its bullion has the ISO currency code for XPT. It is also used as a catalyst in the manufacture of silicone rubber and gel components of medical implants.
According to the National Institute for Occupational Safety and Health the recommended exposure limit to platinum salts is 1mg per cubic meter over an 8-hour working day. Exposure to platinum salts may cause irritation to the eyes, nose, and throat. The long term effects may manifest in the form of skin allergies or respiratory complications (The Centres for Disease Control and Prevention).
According to Anglo-American, South Africa produces 88%, Russia 8%, North America 2%, Zimbabwe 1% and the rest of the world produces 1% of all the platinum. Zimbabwe is the second-largest producer of platinum in Africa. Within the great Dyke are four geological complexes that contain PGM and base metal deposits viz; Wedza Complex (Mimosa-Aquarius and Implats), the Selukwe Complex (Hartley and Ngezi Platinum Mines-Zimplats), Unki Anglo-Platinum and Musengezi geological complex. Zimplats has the largest reserves of PGMs in Zimbabwe which are estimated to be 214.3million tonnes. Unki comes second with 48.4million tonnes and lastly Mimosa with 33.2million tonnes.
In an article written by Freeman Makopa for Newsday, platinum is one of the two minerals, along with diamonds in which the local ownership law requiring 51% local ownership still applies. Due to the desperation, Zimbabwe has for investment, this policy is set to be changed in favor of the foreign investors. At Karo Resources event, Mr. Chitando said, “…We will also have a platinum development policy, which will be unveiled soon in the new year, which will provide a consolidated framework of the development of the platinum sector.” The government is said to have signed a $4.2billion platinum investment deal with Karo resources. The project is expected to reach 1.4million tonnes of platinum per year by 2023.
In the agreement signed on 22 March 2018, KARO HOLDINGS was given PGM rights under a special Grant under the Zimbabwe Mines and Minerals Act covering an area of 23 903ha on the Great Dyke in Mashonaland West. This project will comprise of PGM mines, concentrators, smelters, base metal, and precious metals refinery and a power generation capacity (300MW of solar energy) made available to the power grid. Most recently, Karo has completed 238 boreholes comprising of 32400m drilled on the western boundary of the Great Dyke. the Zimbabwe Special Economic Zones Authority has declared a part of Selous measuring 50667ha as a special economic zone (Tharisa Integrated Innovation)
The price of platinum is heavily dependent on its demand in the industry. In cases where demand is very high, the price can go up to twice the price of gold. As at 05 March 2020, the price of platinum is USD32/g.
In a nutshell, platinum’s rarity is associated with exclusivity and wealth. It is essentially used in medicine, biomedicine, glassmaking equipment, anticancer drugs, oxygen sensors, turbine engines, spark plugs, electrodes and even in investment. Platinum is associated with iron, nickel and copper ores. In its final stages of extraction, it is dissolved in aqua regia from which it emerges in its pure form. Zimbabwe is the second-largest producer of platinum in Africa and produces 1% of the world’s platinum from Zimplats, Unki and Mimosa mines whose ore reserves are estimated to be 214.3 million, 48.4million and 33.2million tonnes respectively. The government has been making efforts to improve platinum production in Zimbabwe by making adjustments to the indigenization policy.
This article first appeared in the March 2020 Issue of the Mining Zimbabwe Magazine