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Utilization of Alum Stone and The Grinding Mill For Alum Stone

Date:2023-08-23 17:13:59    From:    Click:
The alum stone is a widely distributed sulfate mineral that belongs to the tripartite system and serves as the primary source for producing familiar alum. Additionally, alum stone can be utilized in the production of potassium fertilizer, sulfuric acid, and aluminum smelting. It typically appears massive or earth-like with inconspicuous crystals due to its cryptocrystalline nature. When pure, it exhibits a white color; however, impurities cause it to appear light gray, light red, light yellow or reddish-brown with a glassy luster and moderate cleavage at the base. Sodium often replaces potassium in its composition resulting in Natroalunite or natroalingstone when exceeding potassium content while occasionally Fe3+ substitutes Al3+. It is insoluble in water but slightly soluble in sulfuric acid and completely decomposes in strong alkaline solutions.

About Alum Stone


Physical and chemical characteristics

Alingite is a complex sulfate containing hydroxide ion with the chemical formula KAl3[SO4]2(OH)2.  Theoretical values include K2O at 11.37%, Al2O3 at 36.92%, SO3 at 38.66%, and H2O at 13.5%.  Due to its high potassium content, it is often referred to as potassium alingstone;  if Na is replaced by isomorphic K, sodium alingstone can be formed with high sodium content.  Colloidal alingstone rich in adsorbed water is called potassium alum, which may contain rare earth elements.
Alum stone belongs to the trigonal crystal system and often appears as small rhombohedral or thick plates with dense block aggregates, fine granular soil or fiber texture.  It has a white color with light gray, light yellow or light red tones and glass luster.  Its Mohs hardness ranges from 3.5-4 while its density ranges from 2.6-2.9 cleavage medium;  fracture flake to shell.
It's insoluble in cold water and hydrochloric acid but slightly soluble in sulfuric acid while completely soluble in strong alkali sodium hydroxide solution due to its strong thermoelectric effect.


Cause of Formation

The formation of alingite is believed to occur through chemical reactions between sulfur-containing vapors and volcanic rocks such as rhyolite, trachyte, and andesite. This process results in the production of sacs or thin layers within these rocks. Alingite forms as an alteration product of medium acid volcanic extruded rock due to low-temperature hydrothermal activity.

 Application and Development of Alum Stone

The compound is extensively applied across various industries, including manufacturing, chemical processing, food production, agriculture, environmental health, printing and papermaking sectors. It is also utilized as a mordant in textile dyeing processes and as a tanning agent for leather goods and film hardener. Additionally, it serves as a catalyst in synthetic ammonia production and acts as a clarifying agent for sugar refining and water treatment. Furthermore, it functions as a precipitating agent in mineral processing operations. Moreover, the compound serves as raw material for potassium production and alumina synthesis. Its historical significance can be traced back to its widespread use in Europe since the 15th century through mining activities to produce potassium alum.


Alum Making

The scientific name of alum is potassium aluminum sulfate, also known as potassium alum. Its chemical formula is K2SO4·Al2(SO4)3·24H2O, representing a traditional chemical product derived from alum ore. Alum possesses unique physical and chemical properties, such as non-toxicity and high solubility in water. It finds extensive applications in over 40 industries with more than 200 diverse uses, including its utilization for water purification through the precipitation of aluminum hydroxide.
  1. Alum is widely used in various industries, including paper making, pharmaceuticals, dye production, and food processing. In the paper making industry, alum serves as an adhesive and coating agent. In the pharmaceutical industry, it is utilized as a dressing and ingredient in traditional Chinese medicine due to its detoxifying properties and ability to promote fluid balance while also eliminating wind and insects, stopping bleeding, and relieving pain. Western medicine incorporates medicinal aluminum hydroxide, riboflavin (vitamin B2), among other components. Moreover, alum functions as a mordant in the textile and dyeing sector; a tanning agent in leather and fur production; a coagulant in rubber manufacturing; a film hardener; a precipitating agent for mineral processing; and a filling stabilizer for paints and pigments. Additionally, it acts as an additive in preserved preserves and baking powder within the food industry while serving as a water purifier for environmental protection purposes.
  1. The use of alum in agriculture and animal husbandry has always been popular due to its versatile applications. It is commonly used for seed soaking, field fertilization, post-farm work hand and foot cleaning, as well as welding farm tools. In animal husbandry, it serves as a feed additive to promote livestock health and effectively treat diseases such as foot-and-mouth disease, gastric torsion,and ocular ailments.

Processing Shallow Alum Stone Products

The processing of alum ore can be categorized into two methods: raw ore processing and roasted ore processing. The former involves direct processing from the raw ore, while the latter requires roasting and dehydration prior to processing. Roasted ore processing can further be classified into alkali method, acid method, acid-base combination method, chloride method, and water leaching method based on the different leaching reagents used in dehydrated clinker. Through comprehensive utilization and processing of roasted alum ore, various valuable products can be obtained including potassium sulfate, alumina, aluminum hydroxide, sulfuric acid, and 4A zeolite. Potassium sulfate can be directly utilized as a potassium fertilizer for fertilization purposes. Alumina serves as a crucial raw material for electrolytic aluminum production.


Alum Stone Deep Processing Products

Deep processing of aluminum hydroxide and aluminum oxide yields 14 types of fine chemical products, including toothpaste abrasives, flame retardants, desiccants, adsorbents, defluorination agents, catalysts, and carriers. These products have wide applications in the chemical, petrochemical, light industry machinery, electronics medicine and scientific research sectors with significant economic and social benefits. Additionally, precision ceramics made from alumina as well as deep-processed medicinal alumina hydroxide products such as calcined alum and potassium nitrate fertilizers are popular in the market. Over 20 active alumina catalysts and carriers have been developed from raw materials such as α-, γ-, or η-aluminum hydroxides; some have already been applied to devices used in petrochemical refining processes or military operations showing promising prospects.

The Role of Alum Stone In Building Materials is Significant

The use of alum ore in the cement industry has a rich historical background. For example, a mixture of 2 parts kaolinite and alum ore from the Torfa mining area in Italy has gained global attention due to its exceptional mechanical properties that greatly enhance cement strength. China has successfully achieved industrial production of various cement products with diverse properties and applications by utilizing alum stone and its residue. Furthermore, combining alum stone and limestone in the original Portland cement production process equipment results in an economical self-stressed cement variant that is particularly suitable for regions abundant in these resources. Apart from its application in cement production, alum ore also serves as an expansion agent known as EA-L expansion agent for waterproofing and leak-proof construction projects. It is also utilized to produce ESJ agents which provide early strength antifreeze capabilities enabling outdoor construction at temperatures as low as -5°C while maintaining normal setting and hardening characteristics of cement. Additionally, ZM early strength densifier is produced using alum ore as a concrete admixture to improve early strength performance and enhance impermeability. By employing calcined alum stone mixed with 3%~5% anhydrite catalysts, hydration rate can be improved resulting in hardened surfaces that are smooth, delicate, shrinkage-free, and ash-free; making it an ideal material for interior wall plastering.

Alum Stone Grinding Mill

For grinding alum stone powder, Clirik offers two types of grinding machines suitable for processing alum stone. One is the HGM ultra-fine ring roller mill, which can process alum stone to 325-3000 mesh. The other is the CLUM ultra-fine vertical mill, which can process alum stone to 300-3000 mesh.


HGM Ultrafine Grinding Mill

Capacity: 0.2-45 t/h
Feed Size: ≤20 mm
Powder Fineness: 325-3000 mesh

Mill Advantages

  1. Enhanced Energy Efficiency: The system is designed to maximize energy efficiency, ensuring that it operates at optimal levels while minimizing energy consumption. This not only reduces operating costs but also contributes to a greener environment by reducing carbon emissions.
  1. Extended Lifespan of Spare Parts: With a focus on durability and quality, the spare parts used in this system have an extended lifespan. This means fewer replacements are required over time, resulting in cost savings for maintenance and reduced waste generation.
  1. Enhanced Safety Measures: The system incorporates advanced safety features to ensure the well-being of operators and prevent accidents or malfunctions. These measures include robust fail-safe mechanisms, real-time monitoring systems, and emergency shutdown protocols.
  1. Precise Fineness Control with Flexibility: The system offers precise control over the fineness of output materials, allowing for customized adjustments based on specific requirements or applications. Its flexibility enables users to achieve desired results consistently across various production scenarios.
  1. Intelligent Speed Control Technology: Equipped with state-of-the-art intelligent speed control devices, the system automatically adjusts its operational parameters based on real-time data feedback. This ensures optimal performance under varying conditions while maximizing productivity and minimizing downtime.

CLUM Ultrafine Grinding Mill

Capacity: 1-20 t/h
Feed Size: <20 mm
Powder Fineness: 300-3000 mesh

Mill Advantages
  1. The CLUM series ultrafine vertical roller grinding machine has a wide range of applications, capable of processing and grinding various materials such as calcium carbonate, talc, magnesium oxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, limestone, gypsum powder, carbon black and more.
  1. The CLUM series ultrafine vertical roller grinding machine allows for flexible adjustment of the fineness of the processed powder from 325 mesh to 3000 mesh, providing free adjustments.
  1. The CLUM series ultrafine vertical roller grinding machine has a low operating cost. The classifying wheel is made from wear-resistant material and undergoes a heat treatment process to extend its service life. The wearing parts on the grinding wheel and disc are constructed with wear-resistant alloy, reducing replacement costs in severe conditions encountered during barite and steatite processing while minimizing maintenance downtime.
  1. Our optimized CLUM series ultrafine vertical roller grinding machine has a high production capacity. It features enhanced grinding rollers, grinding wheels, diversion system, and internal circulation system that ensure higher grinding efficiency compared to traditional equipment, resulting in an output increase of 10-20%.
  1. Intelligent operation is achieved through the CLUM series ultrafine vertical roller grinding machine, which utilizes PLC control and touch screen operation for automatic production line management. Real-time display and storage of operational data such as speed, temperature, and pressure differential can be achieved. Additionally, complex operations associated with the vertical mill are simplified by enabling automatic feeding based on collected data points such as pressure difference or current. Furthermore, remote control capabilities allow for fault analysis/troubleshooting as well as data analysis through internet connectivity.