Example III: Gypsum block process

　　Since 1990, Liaoning Dongda Powder Engineering Technology Co., Ltd has engaging in the research and development of powder technology and drying, calcination, heat source equipment, and our company is committed to the process and equipment research on the engineering application of natural and chemical gypsum, and has developed the special equipment corresponding to the process. Through continuous accumulation of experience, our company win the outstanding achievement and the recognition from customers in the field of process and engineering system development as well as the manufacturing and application of special process equipment.

　　Under the international promotion of energy saving and environmental protection, Dongda Powder Company focus on the research in the comprehensive application field of chemical gypsum, and in view of the market demand, Dongda Powder Company develops the building gypsum powder process, building block panel process, retarder process, plastering gypsum process, Alpha gypsum process light etc advanced manufacturing process to meet the market and customer demands

Building gypsum powder(ß semi-hydrated gypsum)      Alpha (Þ) gypsum

Gypsum panel                                                                      Self-leveling gypsum flooring

Retarder used in cement                                              Plastering gypsum powder

Introduction to Gypsum Drying and Calcination Process

　　In the production of gypsum products, the calcination is the key step for product quality control. The one-step process, two-step process, Si De calciner, Si De dryer and inside & outside boiling furnace developed by Dongda Powder Company are the processes and equipment which are applicable to different heat sources and different products, and they has formed a complete industrialized system. In selection of calcination system, the purpose of manufactured products, the local heat source, the power conditions, the automation level and the production scale etc should be taken into account so as to determine the calcination method and supporting system.

Process Equipment Features

　　The Si De calciner, which is researched and developed by Dongda Powder Company, is a high efficiency equipment integrated with drying, calcination and break up and is also known as one-step process equipment. It is mainly applicable to calcinate gypsum through the direct heating with the gas from the combustion of heat source (coal, gas or natural gas).

　　Process: in principle, the gypsum to be calcinated is put into this calciner via the feeder, and under the function of mechanical dispersion and hot air generate from the gas, the subject gypsum will experience the dispersion, drying, calcination, high-speed homogenization processes, and the calcinated gypsum will be discharged from the dumping port. The exhaust, after trapping and dust collection, is released from the furnace, and the collected gypsum will be conveyed to the silos.

Two-step Calcination Process System

　　Automatic control, small temperature change range, stable product quality.

　　It can be directly applied in the wet material production, integrating with drying, calcination and break up, low operation cost, reasonable product gradation.

　　Adjustable drying and calcination time, which is convenient to adjust the coagulation time.

　　Applicable to the scaled and continuous production, a variety of heat sources are available, it can apply direct or indirect heating to calcinate, and it also can apply the industrial smoke exhaust from the power plant as heat source.

Two-step Calcination Process System

　　The two-step operation method is composed of drying via Si De dryer and combusting via fluidized outside & inside heating or Si De combustion furnace. The two-step process developed by Dongda Powder Company first considers using the steam from power plant as heat source, and will take the heat-supply network from the steam heat exchanger as the drying heat source. And it uses steam directly or indirectly as heat source for calcination. Dongda Powder Company, according to the user’s heat source manner, determines the two-step process on the basis of the above drying and calcination method.

Example I: Manufacturing gypsum powder (annual output of 100,000 tons)

　　　 Our company cooperated with the Huaneng Wuhan Yangluo Power Plant to develop this annual output of 100,000 tons of desulfurization gypsum production line process and equipment, and it is also the first annual 100,000 tones production line in the power industry in China. This project carried out a successful commissioning at one time at the end of 2008 and had been put into operation. In 2009, it passed the ministry-level authentication. （Photo shows）

　　Our company applies two-step process to carry out drying and calcination for the desulfurization gypsum of power plant. The so-called two-step process is to carry out the drying and calcination in two different equipments respectively. In two-step process, both Si De air drying plus fluidized furnace combination and air drying plus rotary kiln combination are available. Here we introduce the two-step calcination process in which the steam is heat source. The steam as heat source is applicable for the power plant to manufacture semi-hydrated gypsum. Take the steam from the power plant as the heat source, and the steam pressure is generally 0.8~1.6MPa, the steam temperature is 180~300 ℃.

　　The production line in Yangluo Power Plant has the capacity of annual 100,000 tons of building gypsum powder. Take the steam as heat source, and steam temperature is 300 ℃, steam pressure is 1.6MPa. According to desulphurization gypsum feature and by comparison, it applied Si De dryer for drying, and applied fluidized furnace for calcination to manufacture building gypsum powder.

Product Performance Data Obtained from Two-step Calcination Process in Huaneng Yangluo Power Plant

Example II: Manufacturing cement retarder (annual output of 200,000 tons of retarder)

　　Take coal as heat source, use the smoke generating from coal combustion, apply Si De calciner one-step process, after screening for removal of impurity and iron, the generated phosphogypsum will be fed into calciner via conveyor, the calcinated phosphogypsum is mixed with di-hydrated gypsum, and then form spherical retarder products via granulation.

Example III: Gypsum block process

Apply one-step or two-step calcination process to calcinate phosphogypsum or desulphurization gypsum, after further preparation and mixture enter into the block production machine to manufacture the high-strength gypsum building blocks.