【作者】 王斐；

【导师】 仲剑初；

【作者基本信息】 大连理工大学 ， 化学工艺， 2007， 硕士

【摘要】 硼酸钙在我国成为继硼砂和硼酸之后的第三大量硼化学品，目前几乎全部用作无碱玻璃纤维的含硼原料，其次还广泛应用于陶瓷、光学材料、农业、防腐剂、医药、涂料、燃料和电子等行业。我国无碱玻璃纤维工业发展十分迅速，目前每年需要含硼原料达十万吨左右。但我国硼资源基本上是以硼镁矿和硼镁铁矿形式存在，还没有发现可供开采的硼钙矿，其产品主要依赖进口。因此，利用天然硼资源来制备硼酸钙已成为当务之急。本论文研究以钠硼解石（Na₂O·2CaO·5B₂O₃·16H₂O）天然矿粉为原料，采用两种工艺路线制备出硼酸钙产品。第一条工艺路线是用消石灰作为分解剂，钠硼解石矿粉经过分解、过滤、洗涤及干燥制备出偏硼酸钙（CaO·B₂O₃·6H₂O）产品，母液中B₂O₃组份浓度在7—10g／L之间，Na₂O／B₂O₃摩尔比保持在1左右，可认为主要是偏硼酸钠的水溶液。物料配比、反应液固比和时间是分解反应和产品质量的重要影响因素，温度对分解反应影响较小。适宜的工艺条件为：液固比为3.2：1左右；配料硼钙比m（B₂O₃）／m（CaO）在1.45：1左右；温度25℃；反应时间5h左右。制得的硼酸钙产品组成为B₂O₃ 40—42％，CaO 28—31％，Na₂O含量在1.0％左右，MgO含量为2.0％左右，Fe₂O₃含量0.28％左右，可以作为一般低碱和无碱玻璃纤维的含硼原料使用。第二条工艺路线是采用水热法解聚钠硼解石制备硼酸钙。产品物相主要是白硼钙石（4CaO·5 B₂O₃·7H₂O）、硬硼钙石（2CaO·3 B₂O₃·5H₂O）和羟硼钙石（3CaO·2 B₂O₃·9H₂O）；水热解聚得到的多硼酸钠母液可以综合利用制得纯度较高的偏硼酸钙（CaO·B₂O₃·6H₂O）和偏硼酸钠（NaBO₂-4H₂O）副产品。解聚温度是工艺中的关键因素，解聚时间和反应液固比对解聚反应和产品质量、物相也有重要影响。适宜的工艺条件为：温度140℃；时间4h左右；液固比5：1左右，干燥温度高于105℃。制得的硼酸钙产品组成为B₂O₃ 40—42％，CaO 29—32％，Na₂O含量低于0.5％，MgO含量低于1.5％，Fe₂O₃含量为0.25％左右，很好地满足了无碱玻璃纤维工业对含硼原料的要求。研究结果表明：在120℃、液固比大于10的水热条件下，硬硼钙石是比钠硼解石更稳定的硼酸盐矿物；液固比为5、温度较高或时间较长的水热条件下，有利于白硼钙石的生成；温度高于140℃时，硬硼钙石也会转变为白硼钙石或羟硼钙石。更多还原

【Abstract】 Calcium borate has become another staple boron product besides borax and boric acid inChina, which is almost used as boron containing raw material of alkali-free glass fiber atpresent. In addition, it also widely applies in ceramics, optical material, agriculture,preservative, medicine, paint, fuel, electronic industries and so on. Nowadays, China’salkali-free glass fiber industry develops very rapidly, which requires about one hundredthousands of tons boron containing raw material every year. However, the boron resources inChina are basically szaibelyite and ludwigite, and calcium-borate minerals haven’t beendiscovered, which mainly depend on importation. Therefore, it is very urgent to preparecalcium borate from natural boron resources.In this paper, calcium borate product is prepared from natural ulexite mineral（Na₂O·2CaO·5B₂O₃·16H₂O） by two processes. The first process is that ulexite mineral reactswith slaked lime to obtain calcium metaborate hexahydrate （CaO·B₂O₃·6H₂O）. The content ofB₂O₃ in mother liquor reaches 7—10g/L, Na₂O/B₂O₃ mol ratio is about 1. Therefore, borate inthe mother liquor exists in the form of sodium metaborate. Raw material ratio, liquid-to-solidratio and faction time have a great effect on decomposing reaction and quality of the product.The influence of temperature is less. Suitable processing parameters are obtained, i.e.liquid-to-solid ratio, about 3.2:1; m（B₂O₃）/m（CaO） ratio of raw material, about 1.45:1;temperature and time of decomposing reaction, 25℃and about 5h. The contents of B₂O₃ andCaO in the product have reached 40—42% and 28—31％, respectively. The content of Na₂Ois about 1.0％; MgO, about 2.0％; Fe₂O₃, about 0.28％. The calcium borate prepared by thisprocess can be applied to low-alkali and alkali-free glass fiber industry as boron containingraw material.The second process is that ulexite mineral is decomposed to afford calcium borate byhydrothermal method. The phase transformation product is mainly composed of priceite（4CaO·5B₂O₃·7H₂O）, colemanite （2CaO·3B₂O₃·5H₂O） and olshanskyite （3CaO·2 B₂O₃·9H₂O）.The mother liquor of sodium borate can be recovered to prepare higher purity calciummetaborate （CaO·B₂O₃·6H₂O） and sodium metaborate （NaBO₂·4H₂O） as byproduct.Temperature is the key factor of the hydrothermal process. Time and liquid-to-solid ratio playan important role in hydropyrolysis process and affect the quality and phase of the product.Suitable processing parameters are obtained, i.e. temperature and time, 140℃and about 4h; liquid-to-solid ratio, about 5:1; dry temperature, above 105℃. The contents of B₂O₃ and CaOin the product have reached 40—42％and 29—32％, respectively. The content of Na₂O isbelow 0.5％; MgO, below 2.0％; Fe₂O₃, about 0.25％. The calcium borate prepared by thisprocess can meet the requirement of boron containing raw material well in alkali-free glassfiber industry. The research results reveal that colemanite is a kind of more stable phase thanulexite under the hydrothermal condition of 120℃and more than 10 of liquid-to-solid ratio;priceite is formed easily at the higher temperature and longer reaction time with 5 ofliquid-to-solid ratio; at more than 140℃, colemanite can be transformed to priceite orolshanskyite too.更多还原