Mineral Encyclopedia–Gypsum

Gypsum is a common mineral and a sulfate compound of calcium sulfate. It has a unique form and, as a result, a romantic nickname—”desert rose.”

The term “gypsum” generally refers to two minerals: raw gypsum and anhydrite gypsum. Raw gypsum, or dihydrate calcium sulfate (Ca[SO₄]·2H₂O), is also known as soft CaSO₄·2H₂O, hydrous gypsum, or calcium sulfate dihydrate. It belongs to the monoclinic crystal system, with plate-like crystals that are typically dense or fibrous. Its color ranges from white to gray, red, or brown. Moreover, it has a glassy or silky luster, a Mohs hardness of 2, and a density of 2.3 g/cm³.

On the other hand, anhydrite gypsum is anhydrous calcium sulfate (Ca[SO₄]). It has an orthorhombic crystal system and plate-like crystals that are usually dense or granular. Its color is white or light gray, with a glassy luster. Furthermore, the Mohs hardness is 3–3.5, and its density ranges from 2.8 to 3.0 g/cm³. These two types of gypsum are often found together and, under specific geological conditions, can transform into each other.

Additionally, gypsum aggregates can appear in various forms, such as blocky, fine-grained, fibrous, or earthy. Well-developed crystals are typically called transparent gypsum. Fibrous or blocky alabaster with a silky luster is referred to as fibrous gypsum. In some areas with spacious growth environments, alabaster crystals can even form giant crystals, growing up to several meters long.

Gypsum Uses

Gypsum is a versatile industrial and building material with many uses. It can be used as a retarder in cement. It is also used in gypsum-based construction products, model-making, and as a food and pharmaceutical additive. Gypsum plays a key role in sulfuric acid production. It is used as a filler in paper and paint as well.

The microporous structure of alabaster, along with its ability to dehydrate when heated, gives it excellent properties. It provides soundproofing, thermal insulation, and fire resistance. In home decoration, alabaster molding is common. It offers both aesthetic appeal and functional value. When accidents happen, alabaster casts are used in hospitals. They help immobilize and heal bone fractures.

Gypsum is also widely used in art. In galleries and museums, we see lifelike alabaster sculptures.

Gypsum Powder Production Process

The production process of CaSO₄·2H₂O powder mainly includes raw material preparation, crushing, grinding, calcination, cooling, and packaging. The detailed process flow is as follows:

1.1 Raw Material Preparation

• Raw Material Collection: We collect natural alabaster ore from mines or quarries, ensuring the material’s quality and purity.
• Raw Material Screening: We perform initial screening on the collected CaSO₄·2H₂O ore to remove large blocks and impurities, ensuring that the material entering the production line has a uniform particle size.

1.2 Crushing

• Primary Crushing: We use a jaw crusher to carry out the primary crushing of large gypsum ore, reducing it to smaller chunks.
• Secondary Crushing: We then use a cone crusher or impact crusher to further crush the primary material, reducing it to the desired particle size.

1.3 Grinding

• Grinding Equipment: After crushing, we grind the alabaster using Raymond mills, ball mills, or vertical mills to achieve the required fineness.
• Classification and Screening: We use a classifier to separate the ground alabaster powder, ensuring a uniform particle size for the final product.

1.4 Calcination

• Calcination Equipment: We use a rotary kiln or vertical calciner to calcine the ground gypsum powder, removing crystallization water and converting it into β-type hemihydrate alabaster.
• Temperature Control: We strictly control the calcination temperature and time to ensure we achieve optimal calcination results.

1.5 Cooling

• Cooling Equipment: After calcination, we cool the gypsum powder using a cooling machine, preventing high temperatures from affecting the following processes.
• Cooling Speed: We control the cooling speed carefully to maintain the stability of the alabaster powder’s physical and chemical properties.

1.6 Packaging

• Packaging Equipment: Finally, we package the cooled gypsum powder using an automatic packaging machine, ensuring the product is properly sealed and convenient for transport.
• Packaging Specifications: We offer various packaging options based on customer requirements, including bags or drums.

Epic Powder

At Epic Powder, we specialize in providing high-quality gypsum processing solutions, offering cutting-edge grinding equipment and tailored production lines. With over 20 years of expertise in powder processing, our ball mills, roller mills, and air classifier mills ensure efficient grinding, achieving the precise particle size and fineness required for various alabaster applications. Our advanced classification equipment further optimize the alabaster powder production process, ensuring top-notch quality for industrial, construction, and artistic uses. From raw material collection to final packaging, Epic Powder helps streamline alabaster production, enhancing product performance while maximizing efficiency.