Pilot Experiments On The Preparation And Application Of Ultrafine Barium Sulphate

Barium sulfate is a kind of white amorphous nano powder.It can be used for painting,printing,papermaking,plasticmaking,rubbermaking,pharmaceutical,ceramics industry and other industries as filling-agent.Nano-sized barium sulfate has many excellent properties,such as good optical performance,good adsorption,excellent anti-aging properties and good stability.But as its particle size is small,big specific surface area and higher surface energy,the agglomeration is caused easily in the process of drying,and its caking phenomenon is serious.So nano-sized barium sulfate losts the nanoscaleand advantage and its application is limited.At present,foreign countries have developed a small particle size,narrow particle size distribution and good dispersion of nano barium sulfate,used in enamel glaze material,printing paper,surface coating agents,modified plastics industry.The market price is much higher than the common barium sulfate.So the researching focus on producing nano-sized barium sulfate which is small particle size,and narrow distribution and improving its dispersion and stability of nano barium sulfate,but its industrial scale means is less reported.The industrial barium chloride and sodium sulfate as raw materials was used in this paper.The pilot-scale impinging stream reactor was designed.The effects of reactor configuration,impact angle reaction temperature,reactant concentration,feed rate and other conditions on the barium sulfate particle size and morphology.The experimental results showed that at room temperature,when the feature size of the reactor is 5 mm,reactant concentration was 1.2 mol/L,feed rate of reactant was 10.42 m/s,collision angle of two reactant is 90 °,26.76 nm nano-sized barium sulfate is obtained.Industrial pipeline emulsification machine was used for wet method surface modified of nano-sized barium sulfate.The influence of emulsifying machine speed,barium sulfate particle size,modification time,modifier dosage on nano barium sulfate dispersion and activation degree were discussed.Result is as follow: pipeline emulsifier wet method surface modification of nano barium sulfate is suitable for industrial production,when the pipeline emulsification machine speed was 2900 rpm,the modification time was 15 min,the modification temperature was 65 ?,the dosage of modifier was 5%,26.76 nm nano-sized barium sulfate is obtained,the activation reaches to 99.88%,powdered hydrophobic nano-sized barium sulfate has been produed.In view of the small particle size,the large specific surface area,the easy agglomeration of nano-sized barium sulfate,the stability of suspension products was studied by adding dispersant and the ultrasonic method.Stability conditions of suspension product had been optimized.The results showed that when the water and dimethyl sulfoxide were used as dispersing medium respectively,the pH were 10 and 7 respectively,the dispersant were polyacrylic acid sodium,the ultrasonic time was 15 min,the precipitation height of nano-sized barium sulfate were 8.9 cm and 9.7 cm respectively and particles size were 61.79 nm and 89.4 nm respectively and the potential were 38.6 mv and22.3 mv respectively.A good stability system was achieved.