Processes for enhancing filtration rate and/or clarification of phosphoric acid produced by the wet process and containing suspended insoluble particulates by adding to one or more stage of the wet process phosphoric acid production stream an effective amount of a reagent including polymeric microparticles characterized as being anionic or amphoteric and having a weight average molecular weight of greater than 60 Million daltons are provided herein.

Processes for enhancing filtration rate and/or clarification of phosphoric acid produced by the wet process and containing suspended insoluble particulates by adding to one or more stage of the wet process phosphoric acid production stream an effective amount of a reagent including polymeric microparticles characterized as being anionic or amphoteric and having a weight average molecular weight of greater than 60 Million daltons are provided herein.

Processes for enhancing filtration rate and/or clarification of phosphoric acid produced by the wet process and containing suspended insoluble particulates by adding to one or more stage of the wet process phosphoric acid production stream an effective amount of a reagent including polymeric microparticles characterized as being anionic or amphoteric and having a weight average molecular weight of greater than 60 Million daltons are provided herein.

An integrated method for the decadmiation of phosphoric acid includes: etching phosphate with sulphuric acid in a reactor to prepare a phosphoric acid solution containing cadmium and calcium sulphate dihydrate or hemihydrate; concentrating the phosphoric acid solution to form a concentrated phosphoric acid having a mass content between 42% and 61% of P.sub.2O.sub.5; adding sulphuric acid to adjust the free sulphate content, anhydrate being formed by recrystallisation of the calcium sulphate dihydrate and hemihydrate, the cadmium co-crystallising with the anhydrite, to obtain decadmiated phosphoric acid and cadium-rich anhydrite sludge; desulphating the decadmiated phosphoric acid; desaturating and clarifying by decanting the mixture of decadmiated phosphoric acid and sludge; conditioning the sludges with a phosphoric acid solution having a titre by mass of less than or equal to 61% of P.sub.2O.sub.5; and recycling the conditioned sludge in the phosphate etching step.

An integrated method for the decadmiation of phosphoric acid includes: etching phosphate with sulphuric acid in a reactor to prepare a phosphoric acid solution containing cadmium and calcium sulphate dihydrate or hemihydrate; concentrating the phosphoric acid solution to form a concentrated phosphoric acid having a mass content between 42% and 61% of P.sub.2O.sub.5; adding sulphuric acid to adjust the free sulphate content, anhydrate being formed by recrystallisation of the calcium sulphate dihydrate and hemihydrate, the cadmium co-crystallising with the anhydrite, to obtain decadmiated phosphoric acid and cadium-rich anhydrite sludge; desulphating the decadmiated phosphoric acid; desaturating and clarifying by decanting the mixture of decadmiated phosphoric acid and sludge; conditioning the sludges with a phosphoric acid solution having a titre by mass of less than or equal to 61% of P.sub.2O.sub.5; and recycling the conditioned sludge in the phosphate etching step.

A mixing tee assembly suitable for phosphate acid attack reaction is described. The mixing tee assembly comprises an outer pipe having a mixing end and a tee end, wherein a tee structure is formed near the tee end to connect with additional piping; an inner pipe comprising a nozzle end connected to a nozzle and a open end; wherein the inner pipe is lined with a corrosion-resistant material on its inside surface; wherein when the inner pipe is assembled within the outer pipe, the nozzle extends beyond the mixing end of the outer pipe by at least of the inside diameter of the outer pipe.

A mixing tee assembly suitable for phosphate acid attack reaction is described. The mixing tee assembly comprises an outer pipe having a mixing end and a tee end, wherein a tee structure is formed near the tee end to connect with additional piping; an inner pipe comprising a nozzle end connected to a nozzle and a open end; wherein the inner pipe is lined with a corrosion-resistant material on its inside surface; wherein when the inner pipe is assembled within the outer pipe, the nozzle extends beyond the mixing end of the outer pipe by at least of the inside diameter of the outer pipe.

Disclosed herein are compositions and methods of mitigating scale in phosphoric acid and ammonium phosphate plants. Scale-mitigating compositions of the invention can be added to phosphoric acid before or during the concentration in the evaporator cycle of a phosphoric acid plant. The compositions retard the formation of scale on surfaces in contact with the phosphoric acid, and thus time between cleaning is extended and plant productivity increased. Further, the scale that forms is softer and more easily cleaned from surfaces, reducing non-operation time of the plant and/or evaporator. Methods of mitigating scale formation in phosphoric acid production and phosphoric acid handling plants are disclosed. In the methods, scales accumulate more slowly and are softer, more tractable, and more easily cleaned from surfaces to which they adhere.

The invention relates to a method for preparing an aqueous suspension of at least one phosphate material, comprising, dispersing, in water, particles of phosphate material in the presence of at least one additive of the anionic polymer of acrylic acid or of methacrylic acid type. The suspension according to the invention has a viscosity of less than 1500 mPa.Math.s. The invention also relates to the conditioning of the phosphate material associated with the anionic polymer, for its subsequent treatment with at least one strong acid, for the industrial preparation of phosphoric acid.

The invention relates to a method for preparing an aqueous suspension of at least one phosphate material, comprising, dispersing, in water, particles of phosphate material in the presence of at least one additive of the anionic polymer of acrylic acid or of methacrylic acid type. The suspension according to the invention has a viscosity of less than 1500 mPa.Math.s. The invention also relates to the conditioning of the phosphate material associated with the anionic polymer, for its subsequent treatment with at least one strong acid, for the industrial preparation of phosphoric acid.