Introduction of aluminum compound products that can be produced from aluminum dross

Introduction of aluminum compound products that can be produced from aluminum dross

Introduction of aluminum compound products that can be produced from aluminum dross

Secondary aluminum dross contains aluminum oxide and a small amount of metallic aluminum, aluminum nitride and aluminum carbide, etc.

The total aluminum content is more than 55% in terms of aluminum oxide.

The aluminum contained in the aluminum dross after harmless disposal is mainly aluminum oxide or aluminum hydroxide, which can be used as raw materials to produce a variety of aluminum compound products.

Brightstar Aluminum Machinery has long been committed to the research of harmless disposal and resource utilization technology of aluminum dross, in cooperation with scientific research institutions and research colleges, has developed a series of industrialized practical technologies for producing aluminum compounds from aluminum dross.

In order to expand new ways of resource utilization of aluminum dross and serve the development of the aluminum dross resource utilization industry, this article briefly introduces the aluminum compound products that can be produced using aluminum dross, benefiting the development aluminum dross resource utilization industry.

1. Aluminum sulfate

It is obtained by leaching aluminum from aluminum dross with industrial sulfuric acid or waste sulfuric acid as the leaching agent, and then filtering, purifying, crystallizing, separating and drying.

Physical and chemical properties

Aluminum sulfate is a white or off-white powdery crystal.

It is easy to absorb moisture and form lumps when stored in the air for a long time.

It is easily soluble in water, and its aqueous solution is acidic.

It is difficult to dissolve in alcohol.

The supersaturated solution crystallizes into 18-hydrate colorless monoclinic crystals at room temperature, and crystallizes into 27-hydrate below 8.8℃.

It starts to dehydrate at 86.5℃ and loses crystal water when heated to 250℃.

Anhydrous aluminum sulfate begins to decompose when heated to 530℃, and decomposes into γ-Al2O3, SO2, SO3, etc. at 860℃.

The anhydrous substance is a white crystal with pearl luster, and the crude product is an off-white crystal with a porous structure.

Applications

Aluminum sulfate is mainly used as a paper sizing agent and a flocculant for drinking water, industrial water and wastewater treatment.

It is also used as a raw material for producing artificial gemstones and other aluminum salts, such as ammonium alum, potassium alum, and aluminum stearate.

In addition, it is also widely used as a grease clarifier, petroleum deodorant and decolorizer, concrete waterproofing agent and rainproof cloth raw material, mordant, tanning agent, medical astringent, wood preservative, and foam fire extinguishing agent, etc.

Market status and prices

In 2023, the scale of China’s aluminum sulfate market is about 3 billion to 3.5 billion CNY, and it is expected to grow to 3.2 billion to 3.8 billion CNY by 2024, with a production capacity of about 1.35 million tons/year.

China is one of the important producers and exporters of aluminum sulfate.

In recent years, China’s aluminum sulfate exports have increased year by year, mainly exported to Hong Kong, Vietnam, Malaysia and other places.

At the same time, China also imports a certain amount of aluminum sulfate to meet the needs of the domestic high-end market.

The active import and export trade provides a broader development space for the aluminum sulfate market.

At present, the market price of aluminum sulfate is between 800 and 1,300 CNY/T.

2. Sodium aluminate

It is made by mixing aluminum dross with a conversion agent, and undergoing conversion, leaching, purification, evaporation and crystallization.

Physical and chemical properties

Sodium aluminate has two products: liquid and solid.

The liquid is a colorless, transparent, viscous solution, and the solid is a white amorphous crystalline powder.

The molar ratio of sodium oxide to aluminum oxide is between 1.05 and 1.5 for solid products and between 2 and 6.5 for liquid products.

Sodium aluminate is hygroscopic.

The hydrate is obtained by crystallization of concentrated sodium aluminate solution.

It is soluble in water.

The aqueous solution is strongly alkaline and can absorb water to decompose into aluminum hydroxide.

Application

Sodium aluminate is mainly used for surface coating treatment in the production process of titanium dioxide, plugging agent, cement accelerator, filler in the papermaking industry, purifier for industrial water and tap water, alkaline washing solution inhibitor for glass and ceramic etching, and soil hardener.

In addition, sodium aluminate is also widely used in petrochemical, pharmaceutical, rubber, printing and dyeing, steel, textile, and catalyst production.

Market status and price

In 2023, China’s sodium aluminate production will be about 1.5 million tons.

With the rapid development of downstream chemical, pharmaceutical and water treatment industries, the market demand for sodium aluminate is also increasing.

Currently, the market price of sodium aluminate is around 7,000CNY/T.

3. Sodium aluminosilicate

It is prepared by mixing aluminum dross with a converter, converting and leaching to obtain a precursor, adjusting the chemical composition of the precursor with silicate as an adjusting agent, and then crystallizing, filtering, washing and drying.

Physical and chemical properties

Sodium aluminosilicate is a very fine amorphous particle with unique physical and chemical properties.

It is white or off-white powder, odorless, tasteless, with a molecular formula of Na2O·nAl2O3·mSiO2, a relative density of 2.6, a melting point of 1000~1100℃, and is insoluble in water, ethanol or other organic solvents.

It is partially soluble in strong acid or strong alkali solutions at 80~100℃.

Sodium aluminosilicate has a high melting point, thermal stability and acid and alkali resistance.

Application

Sodium aluminosilicate is widely used in coatings, inks, plastics, rubber, leather, printing and dyeing, papermaking, chemicals, ceramics, glass, metallurgy, detergents, environmental protection and other fields.

For example, in the chemical industry, it is used as a catalyst carrier, adsorbent, ion exchanger, etc.

In the metallurgical industry, it is used as a flux, desulfurizer and binder, etc.

In the ceramic industry, it is used as a glaze, embryo raw material and flux, etc.

In the glass industry, it is used as a glass clarifier, flux and emulsifier, etc.

In the environmental protection field, it is used as an environmentally friendly material for wastewater and waste gas treatment, etc.

In the fields of plastics and rubber, it is used as a filler.

Market status and price

With the rapid development of the glass and ceramic industries and the continuous expansion of application fields, the demand for sodium aluminosilicate is also increasing year by year.

In 2023, the annual output of sodium aluminosilicate in Chia will exceed one million tons, and the market size will exceed tens of billions of CNY.

The price of sodium aluminosilicate is between 6,000 and 13,000 CNY/T.

4. Aluminum hydroxide

Aluminum dross is mixed with alkali and reacted to obtain sodium aluminate solution, which is purified, seeded, carbonized, filtered, washed and dried.

Industrial aluminum hydroxide and flame retardant aluminum hydroxide can be obtained by controlling the process conditions.

Physical and chemical properties

Aluminum hydroxide has the chemical formula Al(OH)3, molecular weight 78, and pure product is white crystal or powder.

The crystals are mainly monoclinic gibbsite, also known as α-alumina trihydrate and bayerite, also known as β-alumina trihydrate.

Amorphous powder exists in the form of alumina hydrogel. It loses water when heated and decomposes into alumina.

It is insoluble in water and ethanol, but soluble in hot hydrochloric acid, sulfuric acid and strong alkali.

It is an amphoteric compound that can react with both acid and strong alkali.

Application

Aluminum hydroxide can be used as a pigment and filler in paper, ink, various art pigments, as a color developer in glass and enamel, as a lubricant component, used to make waterproof fabrics, and as a raw material for the production of various aluminum salts.

Aluminum hydroxide is also the largest and most widely used inorganic flame retardant additive.

As a flame retardant, aluminum hydroxide is not only flame retardant, but also can prevent smoke, no dripping, and no toxic gas.

Therefore, it has been widely used and its usage is increasing year by year.

Scope of use: thermosetting plastics, thermoplastics, synthetic rubber, coatings and building materials industries.

At the same time, aluminum hydroxide is also the basic raw material of aluminum fluoride required by the electrolytic aluminum industry, and aluminum hydroxide is also widely used in this industry.

Market status and price

Currently, the market price of industrial-grade aluminum hydroxide ranges from 2,200 to 4,000 CNY/T depending on the quality.

The ex-factory price of flame-retardant aluminum hydroxide is about 4,000CNY/T.

5. Alumina

Mix aluminum dross and alkali and react to produce sodium aluminate solution, which is purified, seeded, carbonized, filtered, washed and dried to produce industrial aluminum hydroxide.

Control the process conditions to calcine industrial aluminum hydroxide to produce metallurgical grade alumina and activated alumina.

Physical and chemical properties

Alumina is a white powder that is easy to disperse.

Its molecular formula is Al2O3, its molecular weight is 101.96, and its chemical properties are stable.

Industrial alumina is a variety of dehydrated products formed by heating and decomposing alumina hydrate. It is a white amorphous powder.

There are four isomorphous crystals of alumina obtained by low-temperature decomposition.

The most common one is γ-Al2O3, which is a typical amphoteric oxide that is insoluble in water but soluble in acid and alkali. γ-Al2O3 is a porous substance with a large internal specific surface area, high activity, and strong adsorption capacity.

It is called activated alumina in industry.

α-Al2O3 has the strongest and most complete crystal structure, large lattice energy, physical properties similar to natural corundum, and the worst chemical activity. γ-Al2O3 can be converted into α-AlAl2O3 at above 1200℃.

Application

The main types of alumina are metallurgical grade alumina and non-metallurgical alumina.

Metallurgical grade alumina is the main raw material for the production of electrolytic aluminum.

The standard we currently implement is YS/T 803-2023, and it is mainly used in the electrolytic aluminum industry.

Alumina is the basic raw material for producing heat-resistant, wear-resistant and corrosion-resistant products, such as high-aluminum refractory materials, high-strength ceramic products, automobile spark plugs, advanced wear-resistant materials and other products.

The product has high melting point, good thermal stability, high hardness, good wear resistance, high mechanical strength, good electrical insulation, corrosion resistance, and is widely used in stereotyped and unshaped refractory materials, refractory castable binders, wear-resistant abrasives, high-purity refractory fibers, special ceramics, electronic ceramics, structural ceramics, stainless steel, granite and other decorative materials for mirror polishing.

Market status and prices

In 2024, China alumina production will be 85.5223 million tons.

At present, the price of alumina has returned to normal.

The current market price of metallurgical grade alumina is about 3,300 yuan/t.

6. Cryolite

Mix aluminum dross with alkali, leaching and purification to obtain sodium aluminate solution.

Use fluorosilicic acid or sodium fluorosilicate, a byproduct of phosphorus chemical industry, as fluorine source, and convert and separate to obtain fluoridation agent solution.

Mix sodium aluminate solution with fluoridation agent solution, and obtain high molecular weight cryolite through precipitation, separation, washing and drying.

Physical and chemical properties

Sodium hexafluoroaluminate (cryolith) Chemical formula: Na3AlF6, molecular weight: 209.94. Mohs hardness 2.5. Density 2.97 to 3.00 g/cm3.

Pure natural cryolite crystals at room temperature are monoclinic (d-type) prismatic colorless crystals, with an appearance similar to that of a cube.

When mixed with impurities, it is often off-white, light yellow or light red, and black.

It is usually an indivisible dense block with a glassy luster, which is transparent and greasy, and the stripes are white.

It is slightly soluble in water, and the aqueous solution is acidic.

Artificial cryolite usually appears white or off-white and light red.

It is a crystalline powder or sandy granules, odorless, and easily absorbs water and moisture.

Colorless cryolite is easily decomposed by moist air.

At white-hot temperatures, water vapor can convert molten cryolite into alumina, and gaseous HCl can convert cryolite into NaCl and AlF3.

Synthetic cryolite is easily decomposed by sulfuric acid, but cryolite that has been melted and then solidified is difficult to be decomposed by hot concentrated sulfuric acid.

Cryolite can also be dissolved in hydrochloric acid and acetic acid.

Application

It is mainly used as a flux for electrolytic aluminum, which can reduce the electrolytic temperature to below 1000℃. 10-12kg of cryolite is consumed per ton of electrolytic aluminum.

In addition, it can also be used as an opacifier for enamel, a sunscreen and flux for glass or enamel production, an insecticide, a flux for aluminum alloy casting, the production of ferroalloys and boiling steel, and a wear-resistant filler for resin rubber.

Cryolite can be divided into high molecular cryolite and low molecular cryolite according to the molecular ratio of sodium fluoride to aluminum fluoride.

Since the use of high molecular cryolite is superior to low molecular cryolite in terms of environmental protection and economic benefits, high molecular cryolite is generally used as a flux for aluminum electrolysis in various electrolytic aluminum plants in China.

Cryolite is divided into sandy cryolite, granular cryolite and powdered cryolite according to its crystal morphology.

Market status and price

The main consumption area of ​​cryolite in my country is the electrolytic aluminum industry, accounting for 48% of the total.

According to statistics, China electrolytic aluminum production capacity will reach 47.249 million tons in 2023, and the operating capacity will be 42.014 million tons.

Based on the consumption of 10kg of cryolite per ton of electrolytic aluminum, the annual consumption is 420,000 tons.

Together with consumption in other fields, the country needs to consume a total of 875,000 tons of cryolite each year.

The main domestic production enterprises include Duofuduo Chemical Co., Ltd. and Shandong Botao Group Co., Ltd.

With the development of science and technology and the expansion of industrial scale, the demand for the application of cryolite in the fields of electrolytic aluminum industry, glass manufacturing, ceramics, etc. continues to increase.

Especially in the electrolytic aluminum industry, the role of cryolite as a flux is becoming more and more important, which has promoted the growth of the cryolite market.

China’s emphasis on environmental protection has led to higher environmental protection requirements in the production process of cryolite.

Manufacturers need to increase environmental protection investment and adopt more environmentally friendly production processes, which increases production costs and puts pressure on market supply.

At the same time, it is understood that with the continuous improvement of environmental protection requirements, domestic fluorite mining will become more difficult, which will lead to a reduction in the output of traditional cryolite production enterprises, providing development space for cryolite produced by resource recycling.

Currently, the domestic market price of high molecular weight cryolite is 6500~7500 CNY/T.

7. Aluminum fluoride

There are two methods for producing aluminum fluoride using aluminum in aluminum dross, one is the dry method and the other is the wet method.

Dry method: Mix aluminum dross with alkali and leach and purify to obtain sodium aluminate solution.

Treat the sodium aluminate solution to obtain aluminum hydroxide.

Fluorination reaction of aluminum hydroxide and hydrogen fluoride in a fluidized bed to obtain aluminum fluoride.

The quality of the obtained product meets the requirements of AF-0 and AF-1 grades of GB/T 4292-2017 standard.

Wet process: There are many process routes for producing aluminum fluoride from aluminum dross using wet process.

The typical process route is: mixing aluminum ash with alkali, leaching and purifying to obtain sodium aluminate solution.

Treating the sodium aluminate solution to obtain aluminum hydroxide.

Using fluorosilicic acid or industrial hydrofluoric acid, a by-product of phosphorus chemical industry, as a fluorine source, mixed with aluminum hydroxide, through conversion, separation, washing and calcination to obtain aluminum fluoride.

The quality of the obtained product meets the requirements of GB/T 4292-2017 standard AF-2 grade.

Physical and chemical properties

Aluminum fluoride is a colorless or white crystal with the molecular formula AlF3.

Density 3.00g/cm. Melting point 1040℃. Boiling point (sublimation) 1272℃. Slightly soluble in cold water, soluble in hot water.

Difficult to dissolve in acid and alkali solutions, insoluble in most organic solvents, and insoluble in hydrofluoric acid and liquefied hydrogen fluoride.

There is no reaction when heated with liquid ammonia or concentrated sulfuric acid, or when melted with potassium hydroxide.

It is not reduced by hydrogen, does not decompose under strong heat but sublimates, and has very stable properties

It can be partially decomposed into hydrogen fluoride and aluminum oxide by water vapor when heated to 300~400℃.

Application:

It is used to reduce the melting temperature of electrolyte and improve conductivity in aluminum electrolysis industry.

It is also used as flux for non-ferrous metals, flux and glaze component for ceramic glaze and enamel glaze, and inhibitor of side fermentation in essential oil production.

It is used as an inhibitor of side fermentation in alcohol production. It is used as welding fluid in metal welding and used to manufacture optical lenses.

It is also used as a catalyst for organic synthesis and a raw material for artificial cryolite.

Market status and price

Aluminum fluoride is mainly used in the electrolytic aluminum industry.

As China electrolytic aluminum industry enters a period of prosperity, it has driven the rapid development of the aluminum fluoride industry.

In 2024, the domestic aluminum fluoride production capacity will be about 1.1 million tons, of which the anhydrous aluminum fluoride and dry aluminum fluoride production capacity will be nearly 1 million tons, and the fluorosilicic acid wet aluminum fluoride production capacity will be about 100,000 tons.

Domestic aluminum fluoride companies are still mainly based on hydrofluoric acid and aluminum hydroxide gas-solid fluidized bed methods.

Currently, the market price of aluminum fluoride: anhydrous and dry aluminum fluoride is between 10,000 and 12,000 CNY/T, and wet aluminum fluoride is 6,500 to 8,500 CNY/T.

8. Polyaluminium ferric chloride

Mix aluminum dross with industrial hydrochloric acid or waste hydrochloric acid, and obtain liquid polyaluminium ferric chloride through leaching, neutralization, alkalization and polymerization.

Dry the liquid polyaluminium ferric chloride to obtain solid polyaluminium ferric chloride.

Physical and chemical properties

Polyaluminum ferric chloride is developed based on the in-depth study of the hydrolysis and coagulation mechanism of polyaluminum chloride and ferric chloride.

It is a new type of composite amorphous, inorganic polymer water purifier with aluminum as the main component and iron as the auxiliary component (iron content is about 2-3%).

Polyferric chloride combines the advantages of aluminum and iron, and significantly improves the morphology of aluminum ions and iron ions.

The liquid product is brown or reddish brown transparent body without precipitation.

The solid product is brown, reddish brown powder or granular, and is easily soluble in water.

Especially when treating high turbidity water and low turbidity water, the treatment effect is more obvious.

Application

Polyaluminum ferric chloride can be used for drinking water, industrial water, industrial wastewater and domestic sewage treatment.

In addition to the reduction of residual turbidity and color, the coagulation effect also has the advantages of fast floc formation, high adsorption performance, and good sludge filtration and dehydration performance.

Especially when treating high turbidity water, low temperature and low turbidity, the treatment effect is better than alum, polyferric sulfate and ferric chloride.

Market status and price

In 2023, the total domestic production capacity of polyaluminium ferric chloride is about 1 million to 1.2 million tons/year.

It is expected that the total production capacity will increase to 1.1 million to 1.3 million tons/year in 2024. With the acceleration of my country’s industrialization process and the continuous expansion of urbanization construction, the problem of water resource pollution has become increasingly prominent.

As a high-quality water purification agent, polyaluminium ferric chloride has unique advantages in water treatment, especially in the treatment of industrial wastewater and municipal sewage, due to its high efficiency and environmental protection, and the market demand is growing year by year.

At present, the market price of liquid polyaluminium ferric chloride is 180~400 CNY/T, and the solid price is 1000-1400 CNY/T.

9. Oil fracturing proppant

It is made by mixing aluminum dross with auxiliary materials, grinding, mixing, balling, drying, calcining and screening.

Physical and chemical properties

Oil fracturing proppants are natural sand or artificial high-strength ceramic solid particles with a certain particle size and strength, a certain sphericity and gradation.

The function of the proppant is to transport and carry the sand-carrying fluid to fill the cracks after the reservoir is squeezed out of the cracks so that they will no longer close, making it easier for oil and gas to migrate, and thus increasing the output of the oil and gas field.

As a key component of the fracturing fluid, the proppant’s own physical and chemical properties, movement in the cracks, sedimentation and other factors directly determine the conductivity of the sand-filled cracks and the area of ​​the effective support cracks.

Petroleum proppants can be mainly divided into three types, namely quartz sand proppants, artificial ceramsite proppants and coated proppants.

Performance requirements: The proppants must have sufficient compressive strength and wear resistance, be able to withstand the strong pressure and friction during injection, and effectively support artificial fractures.

The relative density of proppant particles should be low to facilitate pumping into the well.

At a temperature of 200 degrees, the proppant particles do not chemically react with the fracturing fluid and reservoir fluid, and the maximum allowable acid solubility should be less than 7%.

According to the crushing resistance, the oil fracturing proppant is divided into four series: 52MPa (7500psi), 69MPa (10000psi), 86MPa (12500psi), and 102MPa (15000psi).

According to the volume density, it is divided into: low density, medium density, and high density.

According to the specifications, it is divided into: 12~20 mesh, 16~20 mesh, 16~30 mesh, 20~40 mesh, 30~50 mesh, 40~60 mesh, 40~70 mesh, 70~100 mesh, etc.

At present, China oil fracturing proppant implements the SY/T 5108-2014 standard.

Application

Oil fracturing proppant is a substitute for medium and low strength proppants such as natural quartz sand, glass balls, and metal balls, and has a good effect on increasing the production of oil and gas.

When deep wells of oil and gas are mined, high closure pressure and low permeability ore beds are treated by fracturing, so that the oil and gas-bearing rock formations are cracked, and the oil and gas are collected from the channels formed by the cracks.

The ceramsite support material is used to enter the formation along with the high-pressure solution to fill the cracks in the rock formation, which plays a role in supporting the cracks from closing due to stress release, thereby maintaining high conductivity and effectively guiding oil and gas into oil and gas wells, thereby greatly increasing oil and gas production and extending the life of the oil wells.

Market status and prices

In 2022, China’s oil proppant production capacity is about 3.702 million tons, and the output is about 2.9812 million tons.

The main types of proppants include quartz sand, ceramsite and resin-coated proppants, among which quartz sand and ceramsite are more widely used because they are cheaper and have lower production costs.

With the increase in global energy demand and the gradual depletion of traditional oil and gas resources, the exploration and utilization of unconventional oil and gas resources has become more urgent, which also provides a broad market space for the development of the oil proppant industry chain.

Oil fracturing proppants are divided into three types: low-density, medium-density and high-density.

The price of high-density oil fracturing proppants is about 1,500 CNY/T.

March 10, 2025