氧化铝拜耳法工艺简介

<p style="margin-top:auto;margin-bottom: auto;text-align:left;line-height:25px;background: white"><span style="font-size:15px;font-family: 宋体;color:#222222">&nbsp;&nbsp;其原理是用苛性钠（</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">NaOH</span><span style="font-size:15px;font-family:宋体;color:#222222">）溶液加温溶出铝土矿中的氧化铝，得到铝酸钠溶液。溶液与残渣（赤泥）分离后，降低温度，加入氢氧化铝作晶种，经长时间搅拌，铝酸钠分解析出氢氧化铝，洗净，并在</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">950</span><span style="font-size:15px;font-family:宋体;color:#222222">～</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">1200</span><span style="font-size:15px;font-family:宋体;color:#222222">℃</span><span style="font-size:15px;font-family:宋体;color:#222222">温度下煅烧，便得氧化铝成品。析出氢氧化铝后的溶液称为母液，蒸发浓缩后循环使用。</span></p><p style="margin-top:auto;margin-bottom: auto;text-align:left;line-height:25px;background: white"><span style="font-size:15px;font-family: 宋体;color:#222222">由于三水铝石、一水软铝石和一水硬铝石的结晶构造不同，它们在苛性钠溶液中的溶解性能有很大差异，所以要提供不同的溶出条件，主要是不同的溶出温度。三水铝石型铝土矿可在</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">125</span><span style="font-size:15px;font-family:宋体;color:#222222">～</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">140</span><span style="font-size:15px;font-family:宋体;color:#222222">℃</span><span style="font-size:15px;font-family:宋体;color:#222222">下溶出，一水硬铝石型铝土矿则要在</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">240</span><span style="font-size:15px;font-family:宋体;color:#222222">～</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">260</span><span style="font-size:15px;font-family:宋体;color:#222222">℃</span><span style="font-size:15px;font-family:宋体;color:#222222">并添加石灰（</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">3</span><span style="font-size:15px;font-family:宋体;color:#222222">～</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">7</span><span style="font-size:15px;font-family:宋体;color:#222222">％）的条件下溶出。</span></p><p style="margin-top:auto;margin-bottom: auto;text-align:left;line-height:25px;background: white"><span style="font-size:15px;font-family: 宋体;color:#222222">&nbsp; 现代拜耳法的主要进展在于：</span><span style="font-size:15px;font-family:宋体;color:#222222">①</span><span style="font-size:15px;font-family:宋体;color:#222222">设备的大型化和连续操作；</span><span style="font-size:15px;font-family:宋体;color:#222222">②</span><span style="font-size:15px;font-family:宋体;color:#222222">生产过程的自动化；</span><span style="font-size:15px;font-family:宋体;color:#222222">③</span><span style="font-size:15px;font-family:宋体;color:#222222">节省能量，例如高压强化溶出和流态化焙烧；</span><span style="font-size:15px;font-family:宋体;color:#222222">④</span><span style="font-size:15px;font-family:宋体;color:#222222">生产砂状氧化铝以满足铝电解和烟气干式净化的需要。</span></p><p style="text-align:left;background:white"></p><p style="margin-top:auto;margin-bottom: auto;text-align:left;line-height:25px;background: white"><span style="font-size:15px;font-family: 宋体;color:#222222">拜耳法的优点主要是流程简单、投资省和能耗较低，最低者每吨氧化铝的能耗仅</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">3×106</span><span style="font-size:15px;font-family:宋体;color:#222222">千卡左右，碱耗一般为</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">100</span><span style="font-size:15px;font-family:宋体;color:#222222">公斤左右（以</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">Na2CO3</span><span style="font-size: 15px;font-family:宋体;color:#222222">计）。</span></p><p style="margin-top:auto;margin-bottom: auto;text-align:left;line-height:25px;background: white"><span style="font-size:15px;font-family: 宋体;color:#222222">&nbsp; 拜耳法生产的经济效果决定于铝土矿的质量，主要是矿石中的</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">SiO2</span><span style="font-size:15px;font-family:宋体;color:#222222">含量，通常以矿石的铝硅比，即矿石中的</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">Al2O3</span><span style="font-size:15px;font-family:宋体;color:#222222">与</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">SiO2</span><span style="font-size:15px;font-family:宋体;color:#222222">含量的重量比来表示。因为在拜耳法的溶出过程中，</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">SiO2</span><span style="font-size:15px;font-family:宋体;color:#222222">转变成方钠石型的水合铝硅酸钠</span><span style="font-size: 15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">(Na2O·Al2O3·1.7SiO2·nH2O)</span><span style="font-size:15px;font-family:宋体;color:#222222">，随同赤泥排出。矿石中每公斤</span><span style="font-size: 15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">SiO2</span><span style="font-size:15px;font-family:宋体;color:#222222">大约要造成</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">1</span><span style="font-size:15px;font-family:宋体;color:#222222">公斤</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">Al2O3</span><span style="font-size:15px;font-family:宋体;color:#222222">和</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">0.8</span><span style="font-size:15px;font-family:宋体;color:#222222">公斤</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">NaOH</span><span style="font-size:15px;font-family:宋体;color:#222222">的损失。铝土矿的铝硅比越低，拜耳法的经济效果越差。直到</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">70</span><span style="font-size:15px;font-family:宋体;color:#222222">年代后期，拜耳法所处理的铝土矿的铝硅比均大于</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">7</span><span style="font-size:15px;font-family:宋体;color:#222222">～</span><span style="font-size:15px;font-family:&#39;Arial&#39;,&#39;sans-serif&#39;;color:#222222">8</span><span style="font-size:15px;font-family:宋体;color:#222222">。由于高品位三水铝石型铝土矿资源逐渐减少，如何利用其他类型的低品位铝矿资源和节能新工艺等问题，已是研究、开发的重要方向。</span></p><p><br/></p>