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CN-122029130-A - Precipitated aluminium hydroxide spheres and method for producing same

CN122029130ACN 122029130 ACN122029130 ACN 122029130ACN-122029130-A

Abstract

The present invention relates to a process for producing precipitated aluminum hydroxide spheres by a continuous process and products made therefrom. The invention also relates to the use of precipitated aluminium hydroxide spheres in particular fields. Precipitated aluminum hydroxide products in continuous loop reactors allow for control of particle morphology (shape), particle size and distribution, and chemical purity, and can be used in many different applications where these products are commonly used.

Inventors

  • HUA DUNWU
  • K.W. Gallis
  • E.G. LUNDQUIST

Assignees

  • 赢创运营有限公司

Dates

Publication Date
20260512
Application Date
20241007
Priority Date
20231016

Claims (15)

  1. 1. A continuous process for preparing an aluminum hydroxide product comprising: (a) Continuously feeding an acidulant and an alkalizing agent into a loop reaction zone comprising a liquid medium stream, wherein at least a portion of the acidulant and the alkalizing agent react in the liquid medium in the loop reaction zone to form an aluminum hydroxide product, wherein at least one of the acidulant or the alkalizing agent comprises aluminum; (b) Continuously circulating said liquid medium through said loop reaction zone; (c) Continuously withdrawing a portion of the liquid medium comprising alkaline product from said loop reaction zone; Wherein process steps (a) to (c) are carried out simultaneously and the liquid medium is maintained in a single reaction temperature range.
  2. 2. The continuous process of any preceding claim, wherein the temperature in the liquid medium is maintained between 50 ℃ and 100 ℃.
  3. 3. The continuous process according to any one of the preceding claims, wherein the process further comprises controlling the temperature of the liquid medium with a heat exchanger in thermal communication with at least a portion of one or more loop reactor tubes.
  4. 4. Continuous process according to any of the preceding claims, wherein the loop reactor tube is heated to between 50 ℃ and 100 ℃, preferably between 60 ℃ and 90 ℃.
  5. 5. The continuous process according to any of the preceding claims, wherein the acidifying agent and the alkalizing agent are fed into the loop reaction zone at different points along the loop reaction zone.
  6. 6. Continuous process according to any one of the preceding claims, wherein the acidifying agent is fed into the loop reaction zone at a rate sufficient to maintain the pH in the liquid medium at a value of from 2.5 to 11, preferably from 7.5 to 9.5.
  7. 7. The continuous process according to any one of the preceding claims, wherein the alkalizing agent comprises an alkaline hydroxide, preferably sodium hydroxide, potassium hydroxide, lithium hydroxide, or comprises sodium aluminate, or a combination thereof.
  8. 8. The continuous process of any preceding claim, wherein the acidifying agent comprises an aluminum salt, preferably aluminum sulfate, aluminum nitrate, aluminum phosphate sulfate, or comprises sulfuric acid, or a combination thereof.
  9. 9. The continuous process of any one of the preceding claims, wherein the alkalizing agent is sodium hydroxide or sodium aluminate and the acidifying agent is aluminum sulfate or sulfuric acid or a combination thereof.
  10. 10. The aluminium hydroxide obtained by the continuous process according to any one of the preceding claims, wherein the aluminium hydroxide particles have a spherical particle morphology and different crystallinity.
  11. 11. The aluminum hydroxide product according to claim 10 wherein the product is aluminum hydroxide having a spherical particle morphology and an amorphous structure.
  12. 12. The aluminum hydroxide product according to claim 10 wherein the product is an aluminum oxide hydroxide having a spherical particle morphology and a semi-crystalline structure.
  13. 13. The aluminium hydroxide product particles according to any one of the preceding claims wherein the BET surface area of the particles is greater than 100 m 2 /g, preferably 130 m 2 /g to 350 m 2 /g.
  14. 14. Use of the aluminium hydroxide product prepared according to any one of the preceding claims as a precursor for forming a spherical crystalline alumina product, as a medical product, as a binder, as a flame retardant, as a flame inhibitor, or as an adsorbent.
  15. 15. Spherical alumina product obtained by using the aluminium hydroxide product prepared according to claims 1 to 13, via a heat treatment at a temperature between 500 ℃ and 1300 ℃.

Description

Precipitated aluminium hydroxide spheres and method for producing same Technical Field The present invention relates to a process for producing precipitated aluminum hydroxide spheres by a continuous process and products made therefrom. The invention also relates to the use of precipitated aluminium hydroxide spheres in particular fields. Background The present invention relates to the preparation of precipitated aluminium hydroxide spheres by a continuous process involving a precipitation reaction of possible acidifying and alkalizing agents, wherein at least one of the reagents comprises aluminium, such as the reaction of sodium hydroxide with aluminium sulphate or sodium aluminate with sulphuric acid. The product produced by this process has a spherical particle shape and is amorphous or semi-crystalline in morphology. The invention preferably focuses on the preparation of precipitated aluminum hydroxides, such as aluminum hydroxide (aluminum trihydroxide) (ATH) and/or aluminum oxide hydroxide (aluminum oxide hydroxide) (pseudo-boehmite (pseudoboehmite)), wherein ATH is in an amorphous form and pseudo-boehmite is in a semi-crystalline form. Aluminum hydroxide (ATH) is used in a variety of fields from medical to industrial applications. ATH is used as an antacid to treat heartburn and can help control blood phosphorus levels in patients with certain kidney diseases. ATH is used in industrial applications as a flame retardant and flame retardant in polymers and is common in polymers for plastics and rubber products and for carpet liners and other household products. Pseudoboehmite, another form of aluminum hydroxide, is used as a binder and adsorbent for Fluid Cracking Catalysts (FCC) and can also be used as a feedstock for alumina production. Aluminum hydroxide has been used commercially for many years and is generally produced by the known Bayer process (Bull. Hist. Chem. 17/18 (1995)). The process starts with the hydrothermal treatment of bauxite, which is a sedimentary rock with a relatively high aluminium content, for example by dissolving it in sodium hydroxide at a temperature of up to 270 ℃ to produce sodium aluminate. The solid waste is then filtered and the aluminium hydroxide is precipitated from the remaining sodium aluminate solution. The aluminum hydroxide may be converted to aluminum oxide or aluminum oxide by calcination in a rotary kiln. A newer method for producing alumina is the boehmite (boehmite) method. Boehmite, which is an alumina hydroxide mineral, aluminum monohydrate, can also be used as a precursor for alumina production. Pure boehmite can be produced by isothermal precipitation (seeding (seeding), multistage precipitation) from supersaturated sodium aluminate solution. After calcination in the rotary kiln, the alumina may be used as smelting grade alumina, or may be used to produce other specialty aluminas. Alternative starting materials and processes, such as aluminum sulfate precipitation, typically result in the formation of amorphous ATH. Spherical aluminum hydroxide can be produced by the aluminum sulfate or sodium aluminate route, however, these processes often require organic (co) solvents or organic surfactants, or the formation of spherical ATH in oil baths. It is therefore of interest to produce aluminium hydroxide in an aqueous environment without additives, using different starting materials and using different methods, to improve control of particle morphology (shape), particle size and distribution and chemical purity, and to clearly provide advantages in the market area where ATH and pseudo-boehmite are commonly used. The prior art of US9,617,162 has disclosed a continuous process for the production of precipitated silica to overcome the disadvantages of the conventional silica production processes. However, this particular prior art does not mention the production of aluminum hydroxide and the effect of this process on the production of aluminum hydroxide. Thus, there is a need for an improved aluminum hydroxide production process that can address the above-described drawbacks of conventional production processes. The present invention meets this need and others. It is therefore an object of the present invention to provide a process for producing spherical aluminum hydroxide particles in amorphous or crystalline form using a continuous loop process. Disclosure of Invention The present invention relates to a process for the preparation of aluminium hydroxide particles by a continuous process involving precipitation reactions of an acidifying agent and an alkalizing agent. It has been unexpectedly found that precipitation of these products in a continuous loop reactor (continuous loop reactor) allows control of particle morphology (shape), particle size and distribution, and chemical purity, but can be used in many different applications where these products are commonly used. Accordingly, in a first aspect, the present invention relates to a process as defined i