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Description

Iron orthophosphate is an inorganic salt of orthophosphoric acid and iron(III), CAS 31096-47-6, formula FeO4P. It is found in nature and industry as an anhydrous salt and as a tetrahydrate (mineral strengite). Belongs to the class of transition metal phosphates; The iron ion in the +3 oxidation state is associated with the tetrahedral phosphate anion, forming a crystal lattice insoluble in water.

Basic Attributes

• CAS No.: 31096-47-6
• Chemical formula: FeO4P
• Molecular weight: 150.82
• Exact weight: 222.930618
• EU number: 239-018-0
• PSA specifications: 96.06000
• XLogP3: 0.38350

Synonyms

• Iron(III) (ortho)phosphate
• Iron phosphate
• Phosphoric acid iron salt tetrahydrate
• Iron(III) phosphate tetrahydrate

Scope of application

The main modern direction is a precursor for the synthesis of cathode material for lithium iron phosphate (LiFePO4) batteries: iron orthophosphate, together with lithium salts and a carbon reducing agent, is calcined to obtain the crystalline structure of olivine, which provides high safety, long cycling life and low cost of batteries compared to cobalt-containing cathodes. In addition, the substance is used as a source of iron for the fortification of food products and feed: the food grade is subject to separate requirements for the content of lead, mercury and chromium(VI), while the battery grade is required for the purity and uniformity of particles. Iron orthophosphate is also used as an inorganic pigment and as a component of anti-corrosion coatings and primers for steel and zinc, where the phosphate forms a protective film on the metal surface.

Safety Information

• Transport codes: NONH for all modes of transport (the substance is not classified as dangerous goods)
• WGK Germany: 3 (severe water hazard)
• Hazard class code: R36/37/38
• Safety instructions: S26-S36
• Hazard Labels: Xi (Annoyance)

Storage and transportation

Store in a dry, ventilated area, in tightly closed containers, away from acids and strong reducing agents. When packaging and weighing, avoid the formation of dust, use eye and respiratory protection - the substance is irritating to the eyes, respiratory tract and skin (R36/37/38). Transportation is not regulated as the transportation of dangerous goods (code NONH), however, due to water hazard class 3, spills of the substance are not allowed near water bodies and sewers.

Features of raw materials and production

In the production of battery materials, two approaches are distinguished: the production of iron orthophosphate by precipitation from solutions of iron salts with phosphate ion (wet method) and the electrochemical method of recovery from waste containing phosphate. Both options ultimately yield FePO4·2H2O, which, after drying and calcination with a lithium and carbon component, turns into the olivine crystal structure LiFePO4. The purity of the initial iron orthophosphate in terms of the content of heavy metal impurities directly affects the capacity and service life of the finished cathode, therefore the battery grade undergoes more stringent control than the technical grade.