The present invention is generally directed to improved processes for the preparation of various phosphorus oxides and phosphoric acid. Phosphorus oxides prepared in accordance with the present invention include phosphorus (III) oxides (e.g., tetraphosphorus hexaoxide (P.sub.4O.sub.6)). Phosphorus (III) oxides such as P.sub.4O.sub.6 are useful products and are also useful as precursors in preparation of other products, including phosphorous acid (H.sub.3PO.sub.3) and other phosphorus-containing chemicals. Certain aspects of this invention are also directed to using various byproducts formed during P.sub.4O.sub.6 production as precursors for the formation of phosphoric acid (H.sub.3PO.sub.4) and P.sub.2O.sub.5. In particular, the present invention is directed to improved processes for the preparation of phosphorus (III) oxides (e.g., P.sub.4O.sub.6) suitable for use in the preparation of phospho-herbicides such N-(phosphonomethyl)glycine (glyphosate) and precursors thereof (e.g., N-(phosphonomethyl)iminodiacetic acid (PMIDA)). The present invention is thus further directed to preparation of these compounds.

The present invention is generally directed to improved processes for the preparation of various phosphorus oxides and phosphoric acid. Phosphorus oxides prepared in accordance with the present invention include phosphorus (III) oxides (e.g., tetraphosphorus hexaoxide (P.sub.4O.sub.6)). Phosphorus (III) oxides such as P.sub.4O.sub.6 are useful products and are also useful as precursors in preparation of other products, including phosphorous acid (H.sub.3PO.sub.3) and other phosphorus-containing chemicals. Certain aspects of this invention are also directed to using various byproducts formed during P.sub.4O.sub.6 production as precursors for the formation of phosphoric acid (H.sub.3PO.sub.4) and P.sub.2O.sub.5. In particular, the present invention is directed to improved processes for the preparation of phosphorus (III) oxides (e.g., P.sub.4O.sub.6) suitable for use in the preparation of phospho-herbicides such N-(phosphonomethyl)glycine (glyphosate) and precursors thereof (e.g., N-(phosphonomethyl)iminodiacetic acid (PMIDA)). The present invention is thus further directed to preparation of these compounds.

A method of reducing the amount propylene chlorohydrin produced in a reaction to make a hydroxypropylated/crosslinked starch comprising removing residual propylene oxide from alkaline slurry. The residual propylene oxide is removed by the dewatering the alkaline slurry or by washing the starch in slurry at a pH of around 10. The starch is then neutralized in an acid solution and recovered from the second slurry and may or may not be washed, depending on whether the slurry while at pH around 10 to make a hydroxypropylated/crosslinked starch having less than 1 ppm propylene chlorohydrin.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.

A method of producing lithium difluorophosphate, the method including: a step of obtaining a first raw material mixture by mixing lithium hexafluorophosphate, at least one selected from the group consisting of an oxide of phosphorus (A) and a lithium salt of a phosphoric acid (B), and a hydrocarbon solvent having from 6 to 12 carbon atoms; a step of obtaining a second raw material mixture by removing at least a part of the hydrocarbon solvent contained in the obtained first raw material mixture; and a step of producing a crude product containing lithium difluorophosphate by reacting the second raw material mixture.

A method of producing lithium difluorophosphate, the method including: a step of obtaining a first raw material mixture by mixing lithium hexafluorophosphate, at least one selected from the group consisting of an oxide of phosphorus (A) and a lithium salt of a phosphoric acid (B), and a hydrocarbon solvent having from 6 to 12 carbon atoms; a step of obtaining a second raw material mixture by removing at least a part of the hydrocarbon solvent contained in the obtained first raw material mixture; and a step of producing a crude product containing lithium difluorophosphate by reacting the second raw material mixture.

A phosphorus production method can include reducing feed containing phosphate ore and providing a silica ratio from 0.3 to 0.7 in a reaction chamber from 1250 to 1380 C. Less than 20% of the phosphate remains in the residue. Another phosphorus production method includes continuously moving a reducing bed through the reaction chamber with the feed agglomerates substantially stable while in the reducing bed. Reaction chamber temperature can be from 1250 to 1380 C. A phosphorus production system includes a barrier wall segmenting the reaction chamber into a reduction zone differentiated from a preheat zone. The bed floor is configured to move continuously from the preheat zone to the reduction zone during operation. A method for producing a reduction product includes exothermically oxidizing reduction/oxidation products in the reaction chamber, thereby adding heat to the reducing bed from the freeboard as a second heat source.

Disclosed is a composite pellet used as a raw material in a kiln process for the production of phosphoric acid, which is of a core-shell structure with an inner ball encapsulated with a shell, the inner ball mainly consists of a inner ball material and a binding agent, and the shell mainly consists of a cladding material and a binding agent; the inner ball material mainly consists of a carbonaceous reductant powder, and phosphate ore powder and silica powder, the inner ball is combined with the shell through the binding agent to form the core-shell shaped structure. The preparation of the composite pellets comprises the steps of preparing the inner ball, preparing the cladding material, forming, drying and solidifying composite green pellets etc. The composite pellets prepared by the present invention have a smaller range of formulation fluctuation, more stable quality, higher strength and better performance.

Phosphorus pentoxide production with fluorine management includes collecting phosphorus from kiln off gas as phosphoric acid containing fluorine and reacting the fluorine in the phosphoric acid with reactive silica to yield fluorosilicic acid. The fluorosilicic acid is removed from the collected phosphoric acid. Fluorine management includes discharging from the kiln a residue containing processed agglomerates and heating the discharged, processed agglomerates and releasing fluorine therefrom. The released fluorine is reacted with reactive silica to yield fluorosilicic acid and the fluorosilicic acid is collected. Fluorine management includes forming a reducing kiln bed with feed agglomerates below a reducing freeboard. Kiln off gas is generated containing phosphorus in the form of elemental phosphorus a) oxidized outside of the kiln to phosphorus pentoxide and collected as phosphoric acid, b) collected as elemental phosphorus, or c) both.