In the process of precipitated barium sulfate production,adopting the combination of dry leaves and disc paddle dryer system of process,equipment structure and working principle of the energy consumption and utilization and good environment are analyzed and compared,affirmed the combination drying system compared with the traditional combination of flash convection drying in the manufacture of barium salt rationality and obvious energy saving effect.

 

　　BaSO4 is colorless crystal orthorhombic system,or the amorphous white powder,non-toxic,decompose in 1450℃.

 

　　Chemically stable,the solubility in water is extremely low,mainly used for paint filling.

 

　　In the process of barium sulfate process,drying is the last procedure,the commonly used at present in China there are many types of drying methods,a rotating flash drying,dry two levels of double blade,rotary drying kiln drying,paddle leaf disc combination drying,the drying mode of production is directly related to the final product quality,affect the product final moisture content,whiteness and other technical indicators.

 

　　Generally can be installed capacity of 40000 t precipitated barium sulfate(a by-product of 22000 tons of sodium sulphide)system,a blade paddle and disc combination drying system,the moisture content of barium sulfate pulp is around 25%,with a white material paste;

 

　　The moisture content of the material should reach 0.2%after final drying,and the surface density is 3.5-3.8 Kg/L.

 

　　Process and equipment

 

　　Selection of process process

 

　　In the process of drying up to 10%of the moisture content of barium sulphate,the material has a process of gradually increasing the viscosity and then becoming loose.

 

　　Choosing a two-blade dryer is suitable for this change.

 

　　Moisture content is less than 10%and the material is loose and liquid,and the disc dryer is chosen.

 

　　Therefore,in this project,the combination of the first two blades and the dry combination of the two blades,the two blades and the disk dryer are the conductive drying machines.

 

　　Process by former process of horizontal spiral centrifuge separation after water cut about 25%of the wet material into the first blade paddle dryer,preliminary drying moisture content 10%the left and right sides,eliminate the after part of the viscosity is loose powder of granular material,again into the disc dryer in dry operations,ultimately meet the requirements of product moisture.

 

　　1.2 blades dryer

 

　　The two-blade dryer is a conductive dryer.

 

　　The body consists of a jacket,a double helix,a shaft,a driving mechanism,a roof and a wet system.

 

　　Double helix conveyer dryer horizontal heating work,shell jacket and transmission shaft ventilation with 0.6 MPa steam drying,wet material from the dryer in the feeding mouth to join dryer on the roof,in turn dry rolling forward constantly under the impetus of the transmission shaft,complete the heat transfer in the process of movement of dry materials operations;

 

　　After drying,it is discharged by the bottom outlet of the other end of the dryer and the conveyor process is finished.

 

　　Feature of 1.3 double blade dryer

 

　　(1)wide blade paddle dryer processing material,can use different hot media,can deal with cream,granular,powder material,can deal with heat sensitive material,but also need high temperature processing of materials;

 

　　The whole drying process airtight operation,sharp turn of material in the process of stirring,mixing,material particles fully contact with the heat transfer surface,in axial interval,material temperature,humidity,mixed degree of gradient is small,so as to ensure the stability of the process;

 

　　Also obtained the higher heat transfer coefficient,heat transfer coefficient is generally can reach 80-350 w/(㎡•K);

 

　　The indirect heating materials of the two blades dryer,without the large amount of air carrying the heat,the energy consumption is relatively low.

 

　　(4)within the drying machine from the material in the release of water vapor from the top of the dryer exhaust pipe directly discharge,ingredient is water vapor,the exhaust gas velocity is low,less dust,no dry products with problems;

 

　　Small environmental pollution and reduced investment in dust recovery equipment;

 

　　It can be used for continuous operation,intermittent operation,low speed mixing and reasonable structure.

 

　　Small wear and low maintenance.

 

　　1.4 disk dryer

 

　　Pan continuous drying machine is a new type of conduction drying equipment,plate continuous dryer vertical work,by the dry plate,trailing arm,several rake the leaves in a rake arm,shaft,gear,shell,etc;

 

　　Wet material from the top of the feeding mouth to join,the dry hollow dish inside access to 250℃heat conduction oil.

 

　　Dry plate is divided into the market and small two kinds,decorate in the horizontal layers inside the dryer,dry plate of stationary,material on the market in harrow leaf driven by the movement in the outgoing,by the side of the edge in the market from falling into the small,the material on the small dish by outward movement,by a small edge in the market,on the material in a dry area by rake leaves conveying,flip,the Archimedes spiral trajectory,in the process of movement by dry heating plate,heat and mass transfer complete drying operations,with each layer from the bottom of the dryer after drying plate,the whole drying process airtight operation,release of water vapor from the material after pulse bag filter dust removal by induced draft fan emissions to the atmosphere.

 

　　Features of 1.5 disc dryer

 

　　(1)in the heating disc,the material being raked leaves slowly push,between material wear and tear is small,the shape,size,change before and after drying is very small,breakage rate is extremely low,the quality of crystal material surface little impact;

 

　　The material temperature control is accurate and easy,and the time of stay of the material can be adjusted precisely.

 

　　The flow direction of the material is single,no return miscible,the drying is uniform,the quality is stable,no mixing is needed.

 

　　(4)disc dryer continuously its configuration is simple,don't need to be equipped with air drying must be configured by the cyclone,do not use hot air as a heating medium,therefore,is not going to happen because of bad air and dust separation with product loss caused by exhaust gas entrainment;

 

　　Continuous operation,airtight operation,high evaporation strength,reasonable humidity gradient distribution,low power consumption and small area.

 

　　Double blade and disc dry combination drying system compared with the flash drying system,under the condition of same production and production,combination drying system can energy saving 30%-40%,but the double blade plate dry combination drying system cost on the high side;

 

　　The combined drying system of the two blades is more expensive and more expensive than the two-stage,two-stage drying system.

 

　　Compared with the rotary drying kiln,the combined drying system of the two blades is larger,the investment is higher,and the product's whiteness is not guaranteed.

 

　　This combination drying machine,throughout the precipitated barium sulfate is widely used in production process,the drying effect is very significant,but also improves the indicators of precipitated barium sulfate.

 

　　The quality of our barium sulphate products is perfectly controlled by water.