Wet Regeneration Of Clay Old Sand And Utilization Of Sewage Sludge

Casting is to pour liquid into the mold to achieve the quality requirements of the metal after cooling solidification,to meet the requirements of the casting process.Casting,as one of the basic technology of modern parts manufacturing,is widely used in various fields of national economic construction.In 2016,China's total casting output reached 47 million 200 thousand tons,ranking first in the world for sixteen years in a row.According to the statistics,more than 90% of the total output of the castings in China is produced by sand casting,and about 60% of the castings produced by sand casting process have adopted the clay sand casting process.In the production of clay sand,1 tons of new sand will be consumed for each production of1 tons of castings.At the same time,1 tons of waste sand will be produced,which not only causes pollution to the natural environment,but also a waste of natural resources.Therefore,in order to solve the discharge problem of clay waste sand,the reclamation technology of clay used sand has been widely concerned by the foundry industry.This subject will take sand clay sand clay sand old sand as the research object,and study the technology of wet regeneration,regenerated sewage treatment technology and recycled sludge resource utilization technology containing sand clay sand and clay sand.It is found that the suitable technological route for wet reclamation of old sand containing sand covered sand cores is "water washing + pickling + roasting".The suitable process parameters are 4 times for the old sand scrubbing at 1200r/min speed,each scrubbing time is 5min,the water sand ratio is 1:1 at the first three scrubbing times and the water sand ratio is 0.5:1 at the fourth scrubbing.After scrubbing,theacid solution is added to the acid solution according to the proportion of each 100 g old sand added to the 0.1g/mol HCl solution 4mL,and then filtrate the water,When the 15 min is calcined at 600,the wet reclaimed sand can be obtained.Using wet method to reclaim sand and mix sand,the casting process has reached the level of new sand.With the technology and process parameters mentioned above,the old sand of core sand core sand clay sand is recycled by wet process,and the resin sand of the core box is mixed with reclaimed sand.The casting process performance also reaches the level of the new sand.It is found that the suitable technological route for the reclaimed wastewater treatment with sand covered sand core sand and clay sand is "flocculation +dispersion + precipitation".The suitable technological parameters are the wet process of recycled wastewater with sand clay sand old sand with coated sand core sand,adding 3% polyaluminum chloride(PAC)solution and 2mL in PAM solution with mass fraction of 0.2%,and then adding 12.5mL of sodium pyrophosphate solution with mass fraction of 5% to disperse and precipitate 3.0min,the supernatant liquid can be recycled water.A good scrubbing effect has been achieved by scrubbing the old sand with sand covered core sand and clay sand by reclaimed water.The purpose of this project is to mix the sludge produced by wet reclamation of sand covered sand core sand with old sand.PEO,alpha starch and dextrin were added to eliminate the harmful components in sludge.It is found that the best technological parameters for preparing mixed soil are polyoxirane 4.2g,alpha starch and dextrin10~14g in each 100 g sludge.The mixed sand produced by wet reclaimed sludge with sand covered sand core sand and clay sand used for preparing mixed soil has reached the level of new sand.