Research On The Surface Modification And Purification Processes Of Quartz Sand

Quartz sand is a very versatile non-metallic mineral, is nearly a hundred kindsof industrial products, raw materials, due to its good heat resistance, corrosion that isrich in resources, low price, etc., widely used in the glass industry, the field ofpacking and production silicon metal casting industry, an organic silicon compound.With the expansion of the field of application of quartz sand, quartz sand of purityand nature of the surface characteristics of demand continue to improve, therefore,study the preparation of high purity quartz sand and quartz sand surfacemodification process, particularly in the area for the enlargement of the quartz sandis in high-tech products is of great significance.The paper as raw material, to Si chuan Le shan quartz mine to study thepurification and modification process of quartz sand. Using washing-acid leaching-roasting-broken water-the second acid leaching process the experimental study onthe separation of quartz sand iron impurity. The effects of acid type, concentration,acid leaching time, temperature and other conditions of iron separation. The resultsshow that the optimization of process parameters for the first acid leachingconditions:10%of the concentration of hydrochloric acid, of acid leachingtemperature of45℃, hydrochloric acid solution and quartz sand mass ratio of5:1, acid leaching time4h; roasting optimal conditions: calcination temperature of800℃, roasting time2h; the secondary acid leaching conditions: concentration ofmixed acid （HF: HCl=1:9）10%, acid leaching temperature of45℃, the qualityof the hydrochloric acid solution and quartz sand ratio of2:1, acid leaching time16h. Under this condition, the SiO2content of the purified quartz sand was 99.9683%, the total impurity content as0.0096%, Fe2O3content for the8×10^-6Technical indicators to achieve a high purity quartz sand.Choose a silane coupling agent KH570and KH550as modifier, the use of wetmodification process modification process of quartz sand, the effects of the modifierhydrolysis conditions, the amount of modifier, modified temperature and themodified time of the modification effect. Determination of oil absorption andactivation index evaluation, optimization of the modified process conditions:hydrolysis of the silane coupling agent KH570change the conditions for the mixedsolvent of ethanol and water, the ratio KH570: water: ethanol=1:1:10,the sexualprocess conditions for the modifier amount of5.0%, a modified temperature of70℃, the modified time of1.5h; KH550silane coupling agent for the modifier, themodified process conditions: Modified dosage of5.0%, a modified temperature90℃the time2h modified. Infrared spectroscopy （FT-IR） analysis indicated that thesilane coupling agent by chemical adsorption effectively coated in the surface of thequartz sand; SEM observation results showed that the modified quartz sandagglomeration is significantly reduced, the dispersion obtained a very goodimprovement..The silane coupling agent KH550and KH570modified quartz sand powder isadded as filler to the epoxy coating, through the quartz sand in the heat resistance ofthe epoxy coating before and after the modification and salt-aqueous testing,comparison, and after adding the modified heat resistance and salt water resistanceof the epoxy coating of quartz sand is greatly improved, and KH550modified better.Observed by scanning electron microscopy （SEM） before and after modificationquartz sand is dispersed in the epoxy coating and compatibility. The results showthat the quartz sand by the silane coupling agent KH550and KH570modified epoxycoatings accumulation phenomenon significantly reduced, good compatibility withepoxy resin.