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 Fourth, since the sulfate required for the production of the present invention is provided by the acid leaching slag itself, the mass fraction of the SO/- contained in the acid leaching slag is 15% or more, and the nanometer is prepared by using the acid leaching residue as the zinc and sulfate raw material of the lithopone. Lide powder products not only realize the resource utilization of acid leaching slag, but also turn waste into treasure, and treat and improve the acidic soil of acid leaching residue to purify the environment. Low production costs and simple operation. The metathesis reaction is carried out in a low-density ammonia system (the metathesis reactant is dissolved in recovered ammonia water), and the crystal nucleus formed is smaller. It is non-toxic and safe. The ammonia solution after synthesis and separation is returned to the leaching. There is no waste water in the whole production process. The produced waste residue meets the national solid waste discharge standard for efflux, conforms to the national industrial policy, and is an environmentally friendly “green” type process.

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TiO2 comes in many different forms. However, only a few of these forms are considered food-grade (acceptable to be added to food). Many studies that raised concern about the safety of TiO2, including the concern for genotoxicity, used forms of TiO2 that are not considered acceptable for use in food and have different properties than food-grade TiO2. Other studies did use food-grade TiO2, but took steps to break the material down into smaller particles than what would normally be found in food.

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