JP7535263B2 - Hydrogen production method and method for reusing the residue - Google Patents

Description

The present invention relates to a method for recycling residues generated in hydrogen production machines when producing hydrogen using aluminum alloys as raw materials.

When aluminum or an aluminum alloy is reacted with an alkaline aqueous solution, hydrogen is generated and the aluminum dissolves in the alkaline aqueous solution as aluminate ions.
When the alkaline aqueous solution is sodium hydroxide, it dissolves as sodium aluminate.
When the alkaline aqueous solution is potassium hydroxide, it dissolves as potassium aluminate.

Water-insoluble aluminum hydroxide is recovered from the aqueous solution of sodium aluminate and potassium aluminate, and the aqueous alkaline solution can be reused.
For example, Patent Document 1 discloses a hydrogen production device that uses recycled aluminum cans.
The present inventors have investigated hydrogen production using, for example, cutting chips generated during the manufacturing process of aluminum die-cast products as the raw material rather than using pure aluminum as the raw material for hydrogen production.
This type of aluminum alloy contains a large amount of various additives such as silicon and copper for the purpose of castability and high strength, and the effects of these additives were investigated and examined, leading to the present invention.

Patent No. 6498156

The present invention relates to hydrogen production using aluminum alloys, and in particular aims to provide a method for reusing residues in hydrogen production using scraps and cutting chips generated during the manufacturing process of various products using aluminum alloys.

The method for recycling hydrogen production residue according to the present invention includes a step of generating hydrogen by reacting an aluminum alloy with an alkaline aqueous solution, and a step of separating the solution components in the aluminum alloy that are dissolved in the alkaline aqueous solution from the solid matter that remains undissolved, and is characterized by recycling the solid matter.

The present invention can recover and reuse components contained in aluminum alloys that do not dissolve in alkaline aqueous solutions, or that dissolve in part but only in small amounts, such as silicon, copper, zinc, magnesium, and nickel.

The present invention can produce hydrogen using chips and scraps of various aluminum alloys as raw materials, and can reuse the alloy components contained therein.

(a) shows the aluminum chips used as a raw material for hydrogen production, (b) shows the residue after hydrogen production, and (c) shows aluminum hydroxide recovered from the reaction solution.

The present invention will be explained below using an example of hydrogen production using aluminum alloy cutting chips, but the present invention is not limited to this.

The aluminum alloy used in the present invention may be any of various alloys specified in JIS, provided that it is not a pure aluminum alloy.
The present invention is particularly effective for casting alloys, which contain many additive elements.
The following experiment was conducted using chips of JIS ADC12, which is used in aluminum die casting, so the chemical composition of JIS ADC12 is as follows.
Si: 9.6-12.0%
Cu: 1.5-3.5%
Mg: 0.3% or less Zn: 1.0% or less Fe: 1.3% or less Ni: 0.5% or less Mn: 0.5% or less The balance is Al

FIG. 1(a) shows the appearance of chips generated during machining of an aluminum die-cast product.
The chips were reacted with an alkaline aqueous solution of sodium hydroxide to produce hydrogen.
After the reaction was completed, the mixture was separated into solid and liquid using a filter. A photograph of the obtained solid is shown in FIG.
The residue that was not dissolved in the alkaline aqueous solution was black in color.
Analysis of the components of this black residue revealed that it contained large amounts of Si, Cu, Mg, Ni, Fe, etc.

On the other hand, in the aqueous solution obtained by solid-liquid separation, among the above-mentioned components, neither Cu nor Ni was detected, and the amount of Si was very small.
Next, the solution was cooled, and the aluminate ions in the solution were precipitated as aluminum hydroxide. The recovered aluminum hydroxide was photographed as shown in FIG.
Aluminum hydroxide is also available for industrial use.
The aqueous solution after recovery of aluminum hydroxide could be reused as an alkaline aqueous solution for hydrogen production.

From the above, it has become clear that when hydrogen is produced by reacting aluminum alloy cutting chips with an alkaline aqueous solution, the additive components contained in large amounts in ADC12 can be recovered as reaction residues.
In this example, chips of ADC12 were used, but the process of the present invention can be applied to a variety of aluminum alloys.
In particular, it is effective to produce hydrogen using cutting chips generated during the manufacturing process of a product, and to utilize not only aluminum hydroxide obtained from the reaction solution, but also components contained in the reaction residue.

Claims (1)

A step of generating hydrogen by reacting aluminum alloy chips with an alkaline aqueous solution;
a step of separating a solution component dissolved in the alkaline aqueous solution from a solid matter remaining in the aluminum alloy that has not been dissolved, and reusing the solid matter;
The aluminum alloy chips are JIS ADC12 chips used in aluminum die casting, containing Si: 9.6 to 12.0% and Cu: 1.5 to 3.5%,
A method for recycling residue from hydrogen production, comprising utilizing silicon and/or copper from the solid material .