An arrangement (100) for production of fully soluble, pure and well defined mono- or di-ammonium phosphates, comprises an extraction section (10), a stripping section (20) and end treatment arrangements (90). The extraction section performs a liquid-liquid extraction of phosphate between a feed liquid (1) comprising phosphoric acid and being essentially free from nitrate ions, and a solvent (5) having a solubility in water of less than 2%. The stripping section performs a liquid-liquid extraction of phosphate between solvent loaded with phosphate and a strip solution (4). The solvent depleted in phosphate is recirculated to the extraction section for further extraction of phosphate. The strip solution is an aqueous ammonium phosphate solution, wherein at least 80% of the ammonium phosphate is monoammonium phosphate and/or wherein the solvent is a water-immiscible alcohol. The end treatment arrangements comprise a source of ammonia (60), an adding arrangement (70), a cooling arrangement (50), a precipitate remover (40) and a recirculation system (80).

The present invention provides a method for preparing battery-grade anhydrous iron phosphate from liquid crude monoammonium phosphate, and belongs to the technical field of chemical industry production. In the present invention, ferrous sulfate solution and liquid crude monoammonium phosphate are used as raw materials, and ferrous iron is oxidized to ferric iron and separates out iron phosphate precipitate under the action of an oxidizing agent to obtain iron phosphate intermediate slurry; and then battery-grade anhydrous iron phosphate is finally obtained through solid-liquid separation, washing, aging, solid-liquid separation, washing, drying, dehydration and breaking up. The method provided by the present invention realizes the resource utilization of liquid crude monoammonium phosphate, has simple process and convenient operation and produces less waste water.

A method for chemical processing of sewage sludge ash comprises dissolving a start material, emanating from sewage sludge ash, in an acid comprising hydrochloric acid. The start material comprising at least silicon and iron compounds. Undissolved residues are separated, whereby a leachate remains. The amount of colloidal silica in the dissolved sewage sludge ash is controlled. At least one of iron and phosphorus is extracted from the leachate by liquid-liquid extraction with an organic solvent. At least a part of a raffinate at least partly depleted in at least one of iron and phosphorus originating from the step of extracting at least one of iron and phosphorus is recirculated for dissolving the start material, emanating from sewage sludge ash. The recirculated part of the raffinate at least partly depleted in at least one of iron and phosphorus comprises chloride ions.

The present invention provides a method for preparing battery-grade anhydrous iron phosphate from liquid crude monoammonium phosphate, and belongs to the technical field of chemical industry production. In the present invention, ferrous sulfate solution and liquid crude monoammonium phosphate are used as raw materials, and ferrous iron is oxidized to ferric iron and separates out iron phosphate precipitate under the action of an oxidizing agent to obtain iron phosphate intermediate slurry; and then battery-grade anhydrous iron phosphate is finally obtained through solid-liquid separation, washing, aging, solid-liquid separation, washing, drying, dehydration and breaking up. The method provided by the present invention realizes the resource utilization of liquid crude monoammonium phosphate, has simple process and convenient operation and produces less waste water.

There is provided a process for preparing a crystalline electrode material, the process comprising: providing a liquid bath comprising the electrode material in a melted state; and introducing a precursor of the electrode material into the liquid bath, wherein the electrode material comprises lithium, a metal and phosphate. There is also provided a crystalline electrode material, comprising lithium substituted by less than 0.1 atomic of Na or K; Fe and/or Mn, substituted by less than 0.1 atomic ratio of: (a) Mg, Ca, Al and B, (b) Nb, Zr, Mo, V and Cr, (c) Fe(III), or (d) any combinations thereof; and PO.sub.4, substituted by less than 20% atomic weight of an oxyanion selected from SO.sub.4, SiO.sub.4, BO.sub.4, P.sub.2O.sub.7, and any combinations thereof, the material being in the form of particles having a non-carbon and non-olivine phase on at least a portion of the surface thereof.