Kawu Musa Idris-Idah, 26th June 2026
This series provides brief insights into minerals underpinning the solar industry.
Apatite is the primary mineral source of phosphate. It accumulates over millions of years and mixes with other minerals, forming “phosphate rock”. Apatite always contains calcium and phosphate. Occasionally, fluorine, chlorine and hydroxide are found therein.
Phosphate rock is extracted from underground mines or open pits, after which it is ground and sent to a processing plant where impurities are removed and apatite content within the rock is increased. The apatite-concentrated rock mixes with sulphuric acid in reactors at temperatures of about 70 – 80°C to produce phosphoric acid (also called wet-process
phosphoric acid) and gypsum as the primary by-product. The resulting phosphoric acid is thus in slurry form, still containing impurities (gypsum, calcium, magnesium, iron etc).
Battery manufacturing requires extremely pure phosphoric acid, else performance and lifespan are negatively affected. Substantial effort goes into filtering out the impurities.
Via vacuum filtration, suspended solids in phosphoric acid are removed. Although, remnant impurities like fluoride compounds still exist after filtration. Steam stripping and silica addition are some of the methods used to remove fluorides from this mixture. More gypsum, clay and silica are removed via clarification. Subsequently, organic solvents like Tributyl phosphate (TBP) or Di-isopropyl ether are then used to selectively extract only phosphoric acid from the mixture. Extraction happens in several stages and after each stage, the purity of phosphoric acid increases. Finally, an extremely pure phosphoric acid is recovered from the solvent and the solvent is recycled. If trace impurities still exist post-extraction, more reagents could be used to remove them. Further treatment occurs via ion exchange polishing and activated carbon treatment. The resulting extremely pure and concentrated phosphoric acid (battery-grade) is mixed with an iron feedstock like iron sulphate or iron oxide in a reactor at a temperature of about 50–90°C, to produce an iron phosphate slurry. Iron phosphate crystals are precipitated out of the slurry and separated. They are washed and dried to form powdery iron phosphate, which also goes through some steps: first, it is homogeneously mixed with lithium carbonate or lithium hydroxide and a carbon source like glucose, sucrose, carbon black etc. that later forms a conductive
carbon coating during calcination. Homogenously mixing in ball mills or high-shear mixers ensures uniform composition in the slurry.
The homogenous slurry undergoes wet milling, enabling more uniformity in the distribution of lithium, iron phosphate and carbon within. The slurry is atomized into fine droplets by a spray dryer. Afterwards, it is heated in a calcination furnace to a temperature of about 600-800°C, in the presence of nitrogen for 5-20 hours. Post-calcination, the material is cooled to produce fine black powder. This final version is used as the cathode active material in lithium iron phosphate battery cells. It is integrated with other components like graphite anodes, separators, electrolytes etc. to form batteries.
The table below provides the highest-ranking producing countries of phosphate rock, as per USGS. Africa has excellent representation in phosphate discussions. The next step would be to extract more value from the battery value chain. African countries should therefore aspire to rank high in batteries’ production tables.
Production (2025)
|
Country |
Production (thousand metric tons) |
|
China |
110,000 |
|
Morocco |
36,000 |
|
United States |
20,000 |
|
Russia |
14,000 |
|
Jordan |
12,000 |
|
Egypt |
5,500 |
|
Brazil |
5,000 |
|
Tunisia |
3,300 |
|
South Africa |
2,200 |
|
Other countries* |
770 |
Reserves
|
Country |
Reserves (thousand metric tons) |
|
Morocco |
50,000,000 |
|
China |
3,400,000 |
|
Egypt |
2,800,000 |
|
Tunisia |
2,500,000 |
|
Russia |
2,400,000 |
|
Algeria |
2,200,000 |
|
Brazil |
1,600,000 |
|
South Africa |
1,500,000 |
|
Other countries* |
800,000 |
*Other countries represents sum total of other minor producers / resource owners. It is a metric that enables comparing a country’s levels to minor producers / resource owners.