高钙镁磷矿预处理的硝酸钙镁浸取液制备氢氧化镁的研究  

Study on preparation of magnesium hydroxide from calcium magnesium nitrate leaching pretreatment of phosphate rock with high content of magnesium and calcium

作　　者：唐彪 唐盛伟[1] TANG Biao;TANG Shengwei(School of Chemical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学化学工程学院,四川成都610065

出　　处：《无机盐工业》2024年第5期87-93,120,共8页Inorganic Chemicals Industry

基　　金：国家重点研发计划项目(2022YFC2904704)。

摘　　要：通过煅烧高钙镁磷矿分解碳酸钙镁盐可有效提高磷矿品位。对煅烧后的磷矿进行水化、浸取得到低镁磷精矿和硝酸钙镁浸取液,对浸取液进一步沉淀以回收制备氢氧化镁。然而,在氢氧化镁生产过程中存在固液分离困难和产品纯度低的问题,系统研究了不同温度下湿滤饼的性质、比阻、沉降性能等。结果表明:较低温度下滤饼吸附水分大、过滤困难、洗涤负担大;当温度升高到70℃时,可有效破坏氢氧化镁胶体,从而减少滤饼对水分的吸附,减轻洗涤负担,显著改善氢氧化镁的沉降性能和过滤性能,沉降速率高达0.051 8 mL/min,过滤比阻低达(5.82±1.1)×10^(11) m/kg,镁的回收率可达72%。进一步对沉淀过程进行模拟分析,提出以分步沉淀方式实现杂质的预分离,从而提高氢氧化镁纯度,使其达到工业级氢氧化镁Ⅲ类合格品的要求。The decomposition of calcium magnesium carbonate salts by calcining phosphate rock with high content of mag-nesium and calcium can effectively improve the grade of phosphate rock.Leachate and phosphate rock with low magnesium content are obtained by further hydrating and leaching the calcined phosphate rock.The leachate is further precipitated to prepare magnesium hydroxide.However,there are difficulties in solid-liquid separation and low product purity in the produc-tion process of magnesium hydroxide.The properties,specific resistance,and settling performance of wet filter cakes pre-pared at different temperatures were systematically studied.The results showed that the filter cakes adsorbed more water at lower temperatures,making filtration difficult and washing burdensome.When the temperature was rised to 70℃,the mag-nesium hydroxide colloid could be effectively destroyed,thus reducing the adsorption of water by filter cake,reducing the washing burden,and significantly improving the settlement and filtration performance of magnesium hydroxide.The sedi-mentation rate was up to 0.0518 mL/min,and the minimum specific resistance of filtration was(5.82±1.1)×10^(11) m/kg.The recovery ratio of magnesium could reach 72%.Further simulation analysis of the precipitation process showed that the two-step precipitation method could realize the pre-separation of impurities,thus improving the purity of magnesium hydroxide,and the product purity could meet the requirements of industrial magnesium hydroxide gradeⅢ.

关 键 词：氢氧化镁 过滤比阻 沉降性能 Visual MINTEQ模拟 

分 类 号：TQ132.2[化学工程—无机化工]