The general term gypsum refers to two minerals, raw gypsum and anhydrite. Raw gypsum is calcium dihydrate (Ca [SO4] 2H2O), also known as dihydrate gypsum or plaster. Anhydrite is anhydrous calcium sulfate.
It is a very important industrial raw material that is widely used in construction, building materials, industrial and artistic models, chemical industry (sulfuric acid production, paper filler, paint filler), agriculture, food processing, pharmaceutical, and many other industries and applications.
The plaster of Paris (also known as hemihydrate gypsum), divided into -type gypsum powder and -type gypsum powder, is formed from gypsum raw materials by heating at a high temperature of 105-200 .
The -type gypsum powder has good crystallinity and solidity, so it can be used in ceramic molds, sculptures, gypsum lines and high-end buildings. The -type gypsum powder is mainly used for mortar levelling, gypsum board production, painting, etc.
Gypsum powder can be used as Portland cement retarder in the concrete industry. In agriculture, because gypsum powder is alkaline, it is possible to sprinkle it into the acidic soil to integrate the ph value of the soil so as to make use of a lot of lands.
In the pharmaceutical industry, gypsum is the main medicine in the famous Chinese medicine " Baihu Tang ", which has a good effect in treating acute high fever and thirsty irritable. In addition, dentists use plaster to make models of gums, and surgeons also use plaster to repair the fractures.
Is gypsum harmful to humans? Is gypsum powder safe to eat? Will gypsum kill plants? Here is a video about how gypsum is used, including its uses in toiletries, food additive, fertilizer, chalks, etc. It also shows the process of gypsum.
In recent years, the gypsum industry has developed rapidly. Gypsum building materials are increasingly welcomed by the market and recognized by society with their applications becoming more and more widespread.
According to the US mining forecast, the world's gypsum demand will increase at a rate of 2.5% in the next few years. It is estimated that the world's gypsum demand will reach 300 million tons in 2030. The total annual consumption of the gypsum board will reach 2.04 billion square meters.
With the increase in the market demand for gypsum powder, the requirements for its production technology are getting higher and higher, so the price has risen accordingly. The price of gypsum powder is generally calculated in tons.
Its price varies with its accuracy and use. The price of gypsum powder is between $ 28.8-$ 403.6 per ton according to its whiteness and fineness. The cooked gypsum powder is about $ 28.8-$ 158.6 per ton, the cooking gypsum is about $ 72.1-$ 317.2 per ton, and the refined gypsum powder is about $ 201.8-$ 720.8 per ton.
1. The ex-factory price of Australian recycled gypsum is $ 35.00 per ton, plus $ 25 per ton freight, which is $ 60.00 per ton at the farm gate, and $ 10.00 per ton to spread. Its purity is measured at 17% S wet weight. Total cost of gypsum supply and application per ton of pure CaSO4.2H20 = (35+25+10) 18.6 17 = $ 76.59 per ton.
2. The ex-factory price of gypsum mined in New South Wales is $ 15 per ton, plus $ 40.00 per ton freight, which is $ 60.00 per ton at the farm gate, and $ 11.00 per ton to spread. Its purity is measured at 15% S wet weight. Total cost of gypsum supply and application per ton of pure CaSO4.2H20 = (15+40+11) 18.6 15 = $ 81.84 per ton.
The world's major gypsum producing countries are the United States, Iran, China, Brazil, Canada, Mexico, Spain, Thailand, etc. The United States, Brazil, China, and Canada are rich in gypsum resources.
The largest consumption area of gypsum is the building decoration material industry, which is mainly used to manufacture gypsum boards for construction and decoration. In many countries, the manufacture of slabs accounts for more than 80% of gypsum consumption.
The mining technology of gypsum ore is divided into two categories: the mining of fibrous gypsum ore and the mining of alabaster, ordinary gypsum and anhydrite mines. Due to the difference in physical and mechanical properties of the ore and surrounding rock, the mining technology of these two kinds of gypsum mines is very different.
Fibrous gypsum has low hardness and its rock consolidating coefficient is 1.2 for parallel fibrous gypsum and 1.5 for vertical fibrous gypsum. Because it is brittle, it will easily become fine ore to be lost. Due to the high price of the ore, most fibrous gypsum mines adopt the longwall method, selective mining and filling method.
The mining techniques of alabaster mine, ordinary gypsum mine and anhydrite mine are similar. The room and pillar mining method (generally 8-12 m in width) and breasting method are adopted. The drilling of gypsum ore is easy, but the explosive consumption is large, generally 0.34 kg/t.
The roller drilling rig is modern new drilling equipment. It is suitable for drilling operations of various hardness of minerals and rocks with the characteristics of high perforation efficiency, low operating cost, high mechanization and automation. At present, it has become a widely used perforation equipment in open-pit mines all over the world.
The excavator is composed of the power plant, working device, swing mechanism, control mechanism, transmission system, moving mechanism, auxiliary equipment, etc. The excavator can also perform pouring, lifting, installation, piling, ramming, and pile pulling operations after changing its working device.
After sieving with the vibrating screen equipment, the finished material conforming to the size is sent to the finished product area, while the large material is returned to the crusher for being crushed again until it meets the required size.
The common gypsum crushing equipment is the jaw crusher with a crushing ratio of 4-6. The jaw crusher, which is often used as the primary gypsum crushing equipment, can crush large pieces of gypsum into 150 mm particle size.
If the gypsum crushed by the jaw crusher cannot meet the particle size requirements, secondary gypsum crushing equipment such as cone crushers, hammer crushers, and impact crushers can be equipped to carry out further medium and fine crushing of gypsum. Specific equipment should be configured depends on the actual needs of the customer.
The crushed gypsum is sent to a ball mill for grinding until 90% of it is less than 149 m (100 mesh). The ground gypsum powder leaves the mill in the form of airflow and is collected in the cyclone separator.
The ball mill is mainly a machine for dry or wet grinding of the crushed gypsum. The machine is mainly used for repeated grinding of the raw materials in the barrel through the steel ball medium in the ball mill to complete the ball grinding operation.
The cyclone separator is suitable for purifying non-viscous, non-fibrous dry dust larger than 1-3 microns. It is purification equipment with simple structure, convenient operation, high-temperature resistance and low equipment cost.
Under the design pressure and air volume conditions, solid particles 10 m can be removed. At the operating point, the separation efficiency is 99%, and within 15% of the operating point, the separation efficiency is 97%. Under normal working conditions, the pressure drop of a single cyclone separator at the operating point is not greater than 0.05 MPa.
The gypsum material is lifted by an elevator and transported into the top silo of the rotary kiln preheater. Then, the gypsum material is evenly distributed into rooms of the preheater through the feeding pipe.
In the preheater, gypsum is heated to about 900 C by the flue gas of the roasting kiln at 1150 C, and about 30% of it is decomposed. Then, it is pushed into the rotary kiln by a hydraulic push rod, and -type hemihydrate gypsum (180240 ), anhydrous gypsum (350 ) and overfired gypsum (450700 ) can be produced.
The gypsum produced after calcining and decomposing in the rotary kiln is sent to the cooler to be cooled to below 100 C by the cold air blown in the cooler and discharged. The gypsum from the cooler is sent to the product warehouse via a vibrating feeder, bucket elevator, and belt conveyor.
Gypsum rotary kiln is a kind of thermal equipment for calcining gypsum. Its appearance and shape are similar to lime rotary kiln and cement rotary kiln. Its main structure includes kiln head, kiln tail sealing device, rotary cylinder, supporting device, back-up roll device, etc.
The finished gypsum clinker calcined in the gypsum rotary kiln produced by Fote has the characteristics of high taste, high purity, easy to control during the production process, high mixing degree of raw materials, uniform raw meal composition, high strength grade of the clinker, with less dust in the grinding process, less fly ash in the calcining process and reasonable price.
The large demand and wide application of gypsum powder have stimulated the prosperity of many industries and fields, so the production of high-quality gypsum powder is the general trend of the gypsum powder industry in the future.
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In the crushing and grinding of metallics for beneficiation, the sizing is normally done to liberate the metals or sulphides for further processing to improve recoveries of the basic metals or minerals. The objective is to reduce the ore in size through various closely controlled stages to that degree of fineness which gives an economic liberation of valuable mineral, but which avoids as much as possible the production of sliming fractions. A different philosophy applies to the crushing and grinding of Gypsum.
Gypsum as a mineral (CaSO42H2O) is number 2 on the Mohs scale of hardness; only Talc is softer. This would lead one to believe that it should be easy, to crush, like coal for example, and our equipment was formerly designed on this basis. Within the past 20 years, however, equipment suppliers guaranteeing their equipment performance have had to beef-up the design. Gypsum just didnt crush like a soft rock. Despite being soft, Gypsum is tough, a factor which is of critical importance when developing equipment specifications.
To prevent excessive delays at this point, proper crusher feed and feeder design is not enough. Close cooperation with the drilling and blasting must be maintained. One of the easiest places for cost reductions is by decreasing the powder usage. Since the emphasis is always on minimum cost per ton, this is looked at closely. However, large rock can cause excessive crusher delays. We have placed the primary crushing in the mining cost center in our accounting. This gives the Mining Superintendents both authority and responsibility to coordinate both activities.
The rock size in our quarries and mines depend on numerous factors. Method of transport (conveyor belts versus trucks), method of loading equipment (shovels, Joy mine type cars, front end loaders, etc.) all of which directly effect the rock sizing to the primary crusher.
In new installations., a single roll, toothed crusher of the heavy-duty type is recommended. The reservation to this is proper engineering of the feed to the crusher. That is, the size crusher feed opening with respect to the size rock anticipated. We have presently in use Jaw, Gyratory, Cone and Single or Double Roll crushers. All of these will work, with the usual criteria for final selection being the mining method (as it effects the size of rock fed to the primary crushing plant); tons per hour required; amount of headroom available for the installation; type of secondary crushing to be employed; and the lowest,capital investment consistent with these requirements.
The most commonly used unit is a Roller Mill with an integrated air separator, a very effective fine grinding machine, but requiring high capital investment. We still use Buhr Stones in few places (flat, circular granite stones operating like, a disc grinder) and Entoleters, Rod Mills and Tube Mills might also be used.