【作者】 李杰；

【导师】 樊占国；

【作者基本信息】 东北大学 ， 冶金物理化学， 2010， 博士

【摘要】 虽然辽宁省硼矿资源较丰富,但是经过50多年硼镁矿的大量开采,省内硼矿贫化趋势明显,平均品位由20世纪60年代初期的18%降至12%左右。事实上,许多硼矿加工企业所用矿石硼品位仅在10%左右。本文以低品位硼镁矿为原料,在硫酸法制备硼酸的基础上,充分回收硼酸母液中的镁资源。整个工艺过程形成闭路循环,没有废液排出。用热力学原理计算、分析研究了硼镁矿中蛇纹石、白云石、与稀酸的反应活性。结果表明,蛇纹石、白云石中的Mg可被稀酸完全浸出。当硫酸用量为理论用量的85%,反应时间为100min,硫酸浓度控制在20%,搅拌速度约为100rmp时,硼酸的浸出率可达93.80%。硼酸一次性收率能达到71.06%。所得硼酸纯度为99.62%,达到了工业硼酸标准(GB 538-90)中一等品的含量(硼酸含量在99.4%～100.8%之间)。硼酸的母液在高压釜内进行高温结晶时,硫酸镁浓度应控制在25%以上,溶液中硫酸镁可被有效回收。当硫酸镁浓度为28%,结晶温度为180℃,结晶时间为4h时,一水硫酸镁能够被有效的回收,其一次性收率可达45.03%。一水硫酸镁的纯度达到96.07%。硼铁矿在电炉或高炉内经熔态选择性还原后实现铁与硼的分离,得到含硼生铁和富硼渣。此工艺称为“火法”硼铁分离路线。富硼渣中B2O3的品位可达到12%～17%。从化学组成上来看,它与焙烧后的硼镁矿相似,可代替硼镁矿作为硼的来源。用热力学原理计算、分析研究了富硼渣中原硅酸镁、硅酸钙镁与稀酸的反应活性。结果表明,原硅酸镁、硅酸钙镁中的Mg可被稀酸完全浸出。在理论研究的基础上,分别用硫酸和盐酸对富硼渣进行浸出试验研究。硫酸酸解富硼渣Ⅱ时,最佳的酸解条件是：浸出温度99℃、硫酸用量为理论用量的95%、浸出液固比为6：1、浸出时间为90min。在此最佳条件下进行试验,B浸出率达到98.76%,Mg浸出率为74.32%。对于硫酸酸解液的利用,不同于一般先进行低温结晶制备硼酸再回收利用硼酸母液中硫酸镁的工艺。而是先进行高温提镁,然后剩余母液再低温结晶硼酸。为充分利用热溶液,节省能源,溶液经过除铁、铝步骤后,趁热直接加入高压釜内升温提镁。最终滤液可打入酸解工序,滤液中的硼酸和硫酸镁可重复回收。整个工艺形成闭路循环,没有废液排放。浸出液中的硫酸镁一次性收率在50%左右,硼酸一次收率可达65%以上。制得的一水硫酸镁的纯度达到95.42%。硼酸纯度为99.27%,达到了工业硼酸标准(GB 538-90)中合格品的标准(硼酸含量大于99.0%)。盐酸浸出富硼渣Ⅱ时,最佳酸解条件为：浸出温度为95℃,酸用量为理论用量的95%,浸出时间为40min,浸出液固比为1:1。对盐酸浸出液进行综合利用,开发了制备硼酸和氢氧化镁工艺,并得到副产品硫酸钙。由此方法制得的硼酸纯度为99.55%,达到了工业硼酸标准(GB 538-90)中一等品的标准(硼酸含量在99.4%～100.8%之间)。氢氧化镁的纯度达到80%以上,副产品硫酸钙纯度达到98.81%。开发了富硼渣熔融钠化-热处理晶化-水浸-结晶制备硼砂工艺。以富硼渣为原料,碳酸钠为钠化剂,在高温下进行熔融钠化,熔渣经热处理晶化后得到钠化渣。钠化渣在常压或加压条件下进行水浸,将硼转移到水溶液中,再调节水溶液的pH值,室温下自然冷却结晶,最终得到硼砂晶体。试验结果表明,适合用本工艺制取硼砂的富硼渣,其化学组成应满足：氧化钙含量小于6%；氧化镁与氧化硅的质量比R应在1.4-2.0区间内；氧化铝含量小于9%。最佳工艺条件为：碳酸钠为理论用量的2.3倍,钠化渣热处理温度为650℃，热处理时间为4.5h,水浸温度为180℃。钠化渣中硼的一次浸出率最高可达87.64%。硼砂产品中主含量达到99.31%,大大高出工业硼砂国家标准(GB/T537-1997)中一等品硼砂的含量95.0%,接近硼砂优等品(99.5%)的含量。更多还原

【Abstract】 Although boron resources in Liaoning Province is rich, the dilution trend of ascharite is clearly after 50 years of substantial mining. The average grade of ascharite decreases from 18% to 12% since the early sixties of the 20th century. Moreover, the average grade of ascharite used in processing enterprises is only about 10%. In this paper, on the basis of preparation of boric acid by sulfuric acid method, we use the low-grade ascharite as the raw material to recover the magnesium sulfate in boric acid mother liquor. Since the whole process is a closed circuit, no waste is discharged. The reactivity of the reactions of diluted acid with serpentine ore and dolomite is analyzed by thermodynamic principles. The results show that the Mg can be completely leached from serpentine ore and dolomite by diluted acid. When the amount of sulfuric acid is 85% of the theoretical amount, sulfuric acid concentration is 20%, reaction time is 100min, stirring speed is about 100rmp, the boron leaching rate is up to 93.80% and the recovery rate of boric acid is 71.06%. The purity of boric acid is 99.62%, which fits the first grade industrial products (boric acid content of between 99.4%-100.8%) according to the industrial standard of boric acid (GB 538-90). In addition, when the boric acid mother liquor crystallizes at high temperature in an autoclave, the magnesium sulfate can be efficiently recycled if the concentration of magnesium sulfate is more than 25%. For example, when the concentration of magnesium sulfate in the solution is 28%, the crystallization temperature is 180℃, and the crystallization time is 4h, the magnesium sulfate can be effectively recycled. The recovery rate and purity of magnesium sulfate monohydrate are 45.03% and 96.07%, respectively.Ludwigite is the most important boron resource in China, the B2O3 reserves of which is 58% of the country total reserves. The Selective reduction of ludwigite in the electrical furnace or blast furnace will result in the Separation of iron and boron. This process will finally produce the boron-rich slag and B-containing pig iron. The grade of the boron-rich slag could up to 12%～17%. Since the obtained boron-rich slag is similar to ascharite in the chemical composition, it could replace the ascharite to be the source of Boron. The reactivity of the diluted acid with Mg2SiO4 and MgCaSiO4 in the boron-rich slag has been analyzed based on the thermodynamic principle. It was showed that Mg in the Mg2SiO4 and MgCaSiO4 can be completely leached by the dilute acid. The sulfuric acid and hydrochloric acid were used in the leaching experiments. The best acid leaching conditions for boron-rich slagⅡby sulfuric acid are:99℃of the leaching temperature,95% of the theoretical amount of the amount of sulfuric acid,6:1 of the ratio of leaching liquid to solid, and 90min of the leaching time. Under this condition, the leaching rates for B and Mg are 98.76% and 74.32%, respectively. To take advantage of sulfuric acid leaching solution, the magnesium was recovered at high temperature first, and then the boric acid was crystallized from the mother liquor. This process is different from the previous technology, in which the boric acid was crystallized at low temperature, and then the magnesium was recovered from the mother liquor. After the process of eliminating iron and aluminum, the hot solution was directly added to the autoclave. Adding the hot solution to the autoclave can use the heat of hot solution to save energy. Final filtrate could be added to acid leaching process, the boric acid and magnesium sulfate can be recovered again. The entire process is a closed circuit, no wastewater is discharged. The recovery rate of magnesium sulfate is about 50% and the recovery rate of boric acid is more than 65%. The purity of magnesium sulfate monohydrate is 95.42%。The purity of boric acid is 99.27%, which fits the qualified products under the industrial standard (GB 538-90) for boric acid (the acid content is greater than 99.0%).The results showed that the best acid leaching conditions for boron-rich slagⅡby hydrochloric acid are:95℃of the leaching temperature,95% of the theoretical amount of the amount of sulfuric acid,1:1 of the ratio of leaching liquid to solid,40 min of the leaching time. To take advantage of leaching solution, the preparation technology of boric acid and magnesium hydroxide process was developed and calcium sulfate was the by-product. The purity of the boric acid obtained by this method is 99.55%, which fits the first grade industrial products under the industrial standard (GB 538-90) for boric acid (acid content of between 99.4%-100.8%). The purity of magnesium hydroxide is greater than 80%, and the purity of the calcium sulfate is 98.81%.In the borax preparation process, the technology route of molten sodium treatment—heat treatment—water leaching—crystallization was developed. The boron-rich slag as the raw material reacts with sodium carbonate at high temperature. After the reaction, the molten slag turns to be Na2CO3-modified slag after heat treated. Na2CO3-modified slag is leached by water at atmospheric pressure or high pressure conditions. The boron could transfer to the aqueous solution and then adjusting the pH value of the aqueous solution. Subsequently, the borax is crystallized in the solution at room temperature. The results show that the chemical composition for boron-rich slag which is suitable for this technology should be met the following factors:the calcium oxide content is less than 6%; the MgO/SiO2 should be within the range of 1.4 to 2.0; alumina content is less than 9%. The optimum technology conditions are as following: the amount of sodium carbonate is 2.3 times of the theoretical amount of sodium carbonate; temperature is 650℃; heat treatment time is 4.5h; leaching temperature is 180℃. The highest leaching rate of boron is up to 87.64% in the Na2CO3-modified slag. The purity of the boric acid is up to 99.31%, significantly higher than the purity of first grade borax (95.0%) of national standards for industrial borax (GB/T 537-1997), close to the high-class borax product (99.5%).更多还原