Search

JP-7857216-B2 - Method for forming aluminum trihydrate

JP7857216B2JP 7857216 B2JP7857216 B2JP 7857216B2JP-7857216-B2

Inventors

  • パンディ，トリダンシュ バハードゥル
  • チェン，チャン リン ジェイソン

Assignees

  • ジェイティーエス オプティマックス ピーティーイー．リミテッド

Dates

Publication Date
20260512
Application Date
20210409

Claims (15)

  1. Method for preparing sodium alumate: - Mixing aluminum scrap with sodium hydroxide at a first predetermined temperature to form a mixture containing the aluminum scrap and sodium hydroxide in a ratio of 1:0.2 to 1:0.7, wherein the aluminum scrap has an aluminum oxide content of 30% or more relative to the total weight of the aluminum scrap; and - filtering the mixture to obtain a first filtrate containing sodium aluminate and a first residue.
  2. The preparation method described above The method according to claim 1, further comprising: - diluting the first filtrate with water; and - mixing the first filtrate with carbon dioxide at a second predetermined temperature to obtain an aluminum trihydrate (ATH) residue and a second filtrate.
  3. The method according to claim 1 or 2, wherein the aluminum scrap has an aluminum oxide content of 60 to 90% relative to the total weight of the aluminum scrap.
  4. The method according to any one of claims 1 to 3, wherein the aluminum scrap is powdered aluminum scrap.
  5. The aluminum scrap has an average particle size of 0.002 to 10.0 mm, according to any one of claims 1 to 4.
  6. The method according to any one of claims 1 to 5, wherein the first predetermined temperature is 50 to 100°C.
  7. The method according to claim 2 , wherein the dilution includes diluting the first filtrate at a dilution ratio of 1.5 to 4.
  8. The method according to claim 2 , wherein mixing the first filtrate with carbon dioxide includes introducing carbon dioxide into the first filtrate at a flow rate of 9 to 20 kg/min.
  9. The method according to claim 2 , wherein the second predetermined temperature is 40 to 100°C.
  10. The method according to claim 2 , wherein mixing the first filtrate with carbon dioxide includes introducing carbon dioxide into the first filtrate for 60 to 180 minutes.
  11. The method according to claim 2 , wherein mixing the first filtrate with carbon dioxide lowers the pH of the first filtrate to 7.0 to 8.6.
  12. The method according to any one of claims 1 to 11, performed at atmospheric pressure.
  13. The method according to claim 2 , further comprising evaporating the second filtrate to form sodium bicarbonate.
  14. The method according to claim 13, wherein the evaporation includes evaporation under reduced pressure.
  15. The method according to any one of claims 13 and 14, further comprising heating the sodium bicarbonate to form sodium carbonate.

Description

Technical field: The present invention relates to a method for forming aluminum trihydrate. Background: Aluminum scrap is a by-product of aluminum smelting and may contain metallic aluminum, aluminum oxide, and other metal oxides. Generally, after the recovery of aluminum from aluminum scrap, the scrap is disposed of by landfill, which can lead to the leaching of toxic metal ions into groundwater, causing water pollution problems and loss of raw materials. Furthermore, when aluminum scrap comes into contact with water, ammonia, hydrogen gas, and other volatile gases may be generated, which can not only pollute the air if improperly stored but can also be a source of fire and explosion. There are several methods for recovering aluminum from aluminum scrap. For example, 85-90% of the aluminum oxide in the scrap can be recovered and purified using acid dissolution and high-temperature sodium hydroxide melting methods. Such methods can recover over 90% of the aluminum in the scrap. However, both methods are energy-intensive and therefore not cost-effective or energy-efficient. Aluminum trihydrate (ATH) can be converted to alumina, and subsequently to aluminum. ATH is also widely used in refractory-protected polymers for use in the electronics and automotive industries. However, these applications represent a small percentage compared to the amount converted to alumina for aluminum production. The weight of the aluminum scrap used and the weight of the recovered wet and dry reaction oxide residues (ROR) are shown;The weight of the aluminum scrap used and the weight of the recovered wet and dry white precipitate residue (WPP) are shown;The percentage purity of the recovered aluminum trihydrate (ATH) is shown;The oil absorption (g/100g) of recovered aluminum trihydrate (ATH) is shown;This shows the whiteness of the recovered aluminum trihydrate (ATH);This shows the water content (by weight) of the recovered aluminum trihydrate (ATH). Detailed explanation: As described above, an improved method for recovering aluminum from aluminum scrap is needed. Generally speaking, the present invention provides an improved method for preparing aluminum trihydrate (ATH). ATH may then be converted to aluminum. In this way, effective aluminum recovery may be achieved from aluminum scrap in an environmentally friendly manner. Furthermore, the method of the present invention utilizes carbon dioxide, thereby helping to reduce carbon emissions. The by-products of this method may also have further applications, thereby making the method advantageous in minimizing waste and reducing resource loss to landfills. According to the first aspect, the present invention relates to a method for preparing aluminum trihydrate (ATH), wherein the method is - Mixing aluminum scrap with sodium hydroxide at a first predetermined temperature to form a mixture (wherein the aluminum scrap has an aluminum oxide content of 30% or more relative to the total weight of the aluminum scrap); - Filter the mixture to obtain a first filtrate and a first residue; The present invention provides a method comprising: diluting the first filtrate with water; and mixing the first filtrate with carbon dioxide at a second predetermined temperature to obtain an ATH residue and a second filtrate. The aluminum scrap may be any suitable aluminum scrap. For example, the aluminum scrap may have an aluminum oxide content of 30-95%, 35-90%, 40-85%, 45-80%, 50-75%, 55-70%, or 60-65% of the total weight of the aluminum scrap. In particular, the aluminum scrap may have an aluminum oxide content of 60-90% of the total weight of the aluminum scrap. Aluminum scrap may contain salts. These salts may include, but are not limited to, silicates, chlorides, fluorides, and nitrates. For example, aluminum scrap may contain sodium chloride. The aluminum scrap may be in any preferred form. For example, the aluminum scrap may be in powder form. The aluminum scrap may be formed into powder by any preferred method known in the art. For example, the aluminum scrap may be processed by physical crushing methods using a hammer, jaw crusher, or a crusher to grind the aluminum scrap. In certain embodiments, the aluminum scrap may be in block form, in which case it may be further processed as described above to convert it into a form more suitable for the purposes of the method of the present invention. The aluminum scrap may be of any suitable size. For example, the aluminum scrap may have an average particle size of 0.002 to 10.0 mm. For the purposes of the present invention, the average particle size may refer to the average height of the aluminum scrap particles or the average width of the aluminum scrap particles. In particular, the aluminum scrap may have average particle sizes of 0.01 to 9.0 mm, 0.05 to 8.0 mm, 0.1 to 7.0 mm, 0.5 to 6.0 mm, 1.0 to 5.0 mm, 2.0 to 4.0 mm, or 2.5 to 3.0 mm. More particularly, the aluminum scrap may have an average particle size of 0.002 to 3.0 mm. The mixing may involv