富硼渣钠化法制备硼砂的实验研究

Experimental study on preparation of borax from boron-rich slag by adding sodium carbonate

采用X射线衍射分析(XRD)方法分析表明,富硼渣中的硼组分主要以Mg2B2O5形式存在,而钠化渣中的硼组分以Na4B2O5和NaBO2晶相形式析出.为提取富硼渣中的硼,考察了热处理温度、碳酸钠加入量、热处理时间、水浸温度等因素对钠化渣中硼浸出率的影响.同时考察了富硼渣中w(Al2O3)、w(CaO)、w(B2O3)、m(MgO)/m(SiO2)4个单因素变化对钠化渣中硼浸出率的影响.结果表明,组成为w(Al2O3)5%、w(CaO)1%、w(B2O3)18%、m(MgO)/m(SiO2)2.0的富硼渣,在热处理温度为650℃,碳酸钠加入量为2.3倍,热处理时间为4.5h,水浸温度为180℃的条件下,钠化渣中硼的一次浸出率可达85.01%.

X-ray diffraction analysis demonstrates that the main phase in the boron-rich slag is Mg2B2O5,and Na4B2O5 and NaBO2in the Na2CO3-modified slag.Thus,significant factors for the leaching rate of boron,such as the heat treatment temperature,the adding amount of Na2CO3,heat treatment time and water leaching temperature,were taken into account.Meanwhile,the influence of four single factors,w（Al2O3）、w（CaO）、w（B2O3）、m（MgO）/m（SiO2）,for the leaching rate of boron of Na2CO3-modified slag were also investigated.Experimental results showed that,when the 2.3 times of theoretical amount of the Na2CO3was added to the boron-rich slag whose constituents are w（Al2O3） 5%,w（CaO） 1%,w（B2O3） 18%,m（MgO）/m（SiO2） 2.0,the leaching rate of boron from Na2CO3-modified slag could reach 85.01% by water leaching at 180 ℃ after 4.5 h heat treatment at 650 ℃.