1, the cause of yellow quartz sand pickling
Quartz sand pickling is wet, pickling is the use of various acids.Such as hydrochloric acid, sulfuric acid, oxalic acid, hydrofluoric acid, etc.Before pickling, the crushing is all done by wet method, and part of it is done by mechanical method, such as hammer, so that the crushed materials contain a large amount of mechanical iron.Mechanical iron and quartz sand react slowly in water, and after a few days the mechanical iron oxidizes to ferric iron and turns red and yellow.Iron oxidizes faster in exposed air if soaked with acid.
The first is part of the pickling quartz sand before adding magnetic separation process, mechanical iron removal before pickling.After pickling, some mechanical iron remained in quartz sand, which was quickly oxidized and polluted by mechanical iron.This causes the quartz sand to turn yellow directly.
The second is that pickling is not complete, the surface acid residue on the surface of quartz particles will also cause yellowing.The surface of quartz sand caused by chloride ions, sulfur ions and so on.
The third is the quartz sand before drying and handling tools contact with secondary pollution (contact with iron oxidation) and yellowing.
Pickling before
After pickling
2.Standard technological process of pickling
Quartz sand crushing -- washing -- magnetic separation -- acid leaching -- washing -- dehydration -- drying
After the quartz sand is broken, wash it with water to remove some impurities.Magnetic separation can remove more than 99% of the mechanical iron.Acid leaching may add various acids as the case may be.Acid leaching equipment must be acid-resistant plastic containers, stainless steel is not recommended.Partial acid corrosion of stainless steel.Acid leaching, if possible, is recommended to use a reaction kettle or a container with heating and stirring.Make acid leaching more thorough and reaction more sufficient.Wash to stir, wash thoroughly.
Iii. Preventive measures
1. Crushing equipment
Type selection must be mechanical iron that can be removed by magnetic separation.Some alloys are extremely hard and wear - resistant, but do not absorb magnetism and cannot be removed.Acid pickling is impossible to remove completely in a given period of time.
2. Carrying tools
Conveyors are best handled with conveyor belts, pumps, or non-ferrous tools.Do not use forklift before crushing.Forklifts are prone to secondary pollution.
3, magnetic separation,
Mechanical crushing produces more mechanical iron, it is best to choose automatic magnetic separation equipment.Manual chute and other magnetic separation equipment magnetic bar or magnetic block number to be enough and hard to clean.If necessary to detect the effect of magnetic separation.
4, acid leaching
Reaction kettle class with stirring equipment to do acid corrosion treatment, plastic container static immersion time and acid concentration ratio.
5, cleaning
Cleaning with stirring cleaning bucket cleaning, bucket can be stainless steel or plastic.Water enters from the bottom of the cleaning barrel and overflows from the cleaning barrel surface.This cleaning effect is the best and fast, to ensure that each quartz sand particles clean.
6, drying
Immediately after cleaning to dehydration, drying.
The yellowing of quartz sand once again emphasizes that it is secondary pollution caused by mechanical iron oxidation reaction, which is caused by oxidation reaction between the container wall and the container wall when the acid is not cleaned and the container is dried.
