TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The dissolution process is carried out at a pH of less than 2, preferably less than 1.5. The method further involves adding sulfide to primary leach solution, precipitating sulfides of heavy metals, separating precipitated sulfides of heavy metals from primary leach solution, adapting an ion proportion in primary leach solution such that the ratio between cations precipitable as phosphate compounds and phosphate ions is increased, when a phosphate mole content in primary leach solution is higher than the molar amount expected to be precipitated during addition of base to primary leach solution is larger than 1. Adapting an ion proportion in primary leach solution involves adding oxidant to primary leach solution before precipitating phosphate compounds and causing ferrous iron to oxidize to ferric iron. The method of recovering phosphate compound involves adding base to portion of phosphorus depleted feed solution, causing aluminum hydroxide to precipitate, separating precipitated aluminum hydroxide from phosphorus depleted solution, producing aluminum depleted feed solution, or adding calcium phosphate and base to phosphorus depleted feed solution, causing aluminum phosphate to precipitate, separating precipitated aluminum phosphate from phosphorus depleted solution, and producing aluminum depleted feed solution. Preferred Composition: The base comprises lime or iron hydroxide. The phosphorus depleted feed solution comprises lime, sodium hydroxide or ammonia.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The method of recovering phosphate compound involves dissolving precipitated phosphate compound into secondary leach solution, providing a feed solution comprising iron phosphate, extracting iron from feed solution with organic solvent (A) comprising tributyl phosphate, modifier and diluent, producing iron depleted feed solution, stripping extracted iron from organic solvent (A) using water and dilute acid, recycling organic solvent (A), and recovering phosphate compounds from iron depleted feed solution. The method of recovering phosphate compounds from iron depleted solution involves extracting phosphoric acid from iron depleted solution with organic solvent (B) comprising tributyl phosphate, a modifier and a diluent, producing phosphorus depleted feed solution, stripping extracted phosphoric acid from organic solvent (B) by an aqueous solution, and recycling organic solvent (B) after stripping of extracted phosphoric acid. Preferred Composition: The organic solvent (A) comprises 5-60 vol.%, preferably 10-40 vol.% tributyl phosphate, and 10-40 vol.% modifier. The modifier is 10-40 vol.% dodecanol. The diluent is aliphatic kerosene. The organic solvent (B) comprises 70-100 vol.% tributyl phosphate.