Gypsum beneficiation processing method

There are many methods that can be used for gypsum beneficiation, such as heavy medium ore dressing, photoelectric ore dressing, flotation and electricity dressing, etc. However, these methods are not widely used in industrial production at this moment. Most of the mines only do simple hand picking for the mined gypsum ores. When mined, fiber gypsum, mud gypsum, common gypsum and a small amount of anhydrite can be mined out by the hand picking.

Calcination process of gypsum

Calcination process of gypsum can be classified into two methods, dry calcination and wet calcination.

1. Dry calcining: under ordinary pressure (or water vapor and low partial pressure), gypsum is heated and dewatered. With temperature changing, there are �� type hydrated gypsum, �� type anhydrous gypsum and overburning gypsum that are produced. This product is commonly used in buildings, such as calcined gypsum, pouring gypsum or the prefabrication gypsum.

2. Wet calcining: under the steam pressure in autoclave, or in the low pressure in the saline solution whose boiling point is higher than 100 ��, the gypsum is heated and the product is �� type hydrated gypsum, which can be used as special gypsum base material pouring.

Gypsum calcining process flow

1. �� type calcined gypsum production process flow: ore storage��crushing��the gypsum homogenization��calcining dehydration�� ageing��grinding and mixed��packing, when using the calcined fry pan, the materials should be ground into powder then calcined.

2. Gypsum dry calcining process: the gypsum is transported from the mining field. Then the gypsum is stored firstly then fine selected to guarantee the continuous feeding materials and stable quality. The feeding materials come through a period of crushing (jaw crusher) and the grain size can be below 8cm. Then through the secondary crushing(hammer crusher), grain size can be below 2cm. Then bucket elevator sends the materials into calcining kiln for the gypsum calcination. Through the control of the temperature in kiln, �� type hydrated gypsum, anhydrous gypsum and overburning gypsum can be produced respectively.

3. �� type wet calcining process flow: gypsum raw materials storehouse��screen��high pressure autoclave and drying crushing��the homogenization storage���� and �� gypsum mixed��packing and handling. Hydrothermal process to produce the �� type hydrated gypsum is that: gypsim raw ore��crushing ��grinding��the reaction kettle (water and potions added)��cleaning��dehydration and drying ��packing.

Gypsum process equipment

1. The commonly used gypsum crushers are Jaw Crusher, Cone Crusher, Impact Crusher, Roller Crusher and Hammer Crusher, etc.
2. Dry calcination often uses two kinds of equipments: direct calcination equipment and indirect calcination equipment. Direct calcination equipments are rotary kiln and grinding calcining integration device(Peter grinding mill, high temperature wind grinding mill, etc). Indirect calcination equipments are rotary calcined furnace, calcined fry pan(soil fry pan can be calcined directly), horizontal calcined furnace and vertical calcined furnace, etc.
3. Wet calcination equipments are horizontal or vertical still kettle and vulcanizing boiler, etc.

Gypsum mineral processing examples

The gypsum is transported from the mining field. Then the gypsum is stored firstly then fine selected to guarantee the continuous feeding materials and stable quality. The feeding materials come through a period of crushing (Jaw Crusher) and the grain size can be below 8cm. Then through the secondary crushing(Hammer Crusher), grain size can be below 2cm. Then bucket elevator sends the materials into calcining kiln for the gypsum calcination.

Rotary kiln is using downflow system. Through the control of the temperature in kiln, �� type hydrated gypsum��180��240�棩, anhydrous gypsum��350�棩 and overburning gypsum��450��700�棩 can be produced respectively. The calcinated gypsum comes through ageing and homogenization. Then the gypsum can be ground into 200-300mesh by pendulous crusher, which is the 4 R-3216 type produced by ZENITH Machinery.