盐湖镁渣的热处理工艺及其对磷酸镁水泥性能的影响

Heat Treatment Technology of Salt Lake Magnesium Slag and Its Influence on the Properties of Magnesium Phosphate Cement

盐湖镁渣是盐湖卤水提取碳酸锂过程中产生的废渣,盐湖提锂产业的不断发展导致大量镁渣的产生和堆积,如何有效利用盐湖镁渣成为盐湖地区生态保障、高效生产的必要条件。本研究以盐湖镁渣为原料对其进行热处理和物理性能分析,并将热处理后的盐湖镁渣与KH_(2)PO_(4)反应制备盐湖磷酸镁水泥(SLMPC),研究盐湖镁渣的热处理工艺对SLMPC凝结时间、抗压强度、水化产物和微观形貌的影响。结果表明:热处理工艺对盐湖镁渣原料和SLPMC的物化性能影响显著,随热处理温度的升高和保温时间的延长,盐湖镁渣的主要物相Mg(OH)_(2)逐渐转化为MgO,其晶粒尺寸和堆积密度增大,比表面积和水化反应活性降低;SLMPC浆体的凝结时间从几分钟延长到33 min,各龄期的抗压强度呈现先升高后降低的趋势,主要水化产物为MgKPO_(4)·6H_(2)O;确定最佳的热处理温度范围为1 000~1 100℃,保温时间为3~6 h。

Salt lake magnesium slag is the waste residue produced in the process of extracting lithium extraction from salt lake brine.Due to the continuous development of lithium extraction industry,a large number of magnesium residues were produced and accumulated.How to effectively utilize these magnesium slags will become the necessary condition for ecological protection and efficient production in salt lake area.Salt lake magnesium slag was used as raw material for heat treatment and physical property analysis in this study,the salt lake magnesium slag after heat treatment was reacted with KH_(2)PO_(4) to prepare salt lake magnesium phosphate cement(SLMPC).The effects of heat treatment process of salt lake magnesium slag on the setting time,compressive strength,hydration products and micro morphology of SLMPC were studied.The results show that the heat treatment process has a significant impact on the physicochemical properties of salt lake magnesium slag raw materials and SLMPC.With the increase of heat treatment temperature and holding time,the main phase Mg(OH)_(2) of salt lake magnesium slag is gradually transformed into MgO,and its grain size and bulk density increase,specific surface area and hydration reaction activity decrease.The setting time of SLMPC slurry is extended from a few minutes to 33 minutes.The compressive strength of each age increased first and then decrease.The main hydration product was MgKPO_(4)·6H_(2)O.The optimum heat treatment temperature range from 1000 to 1100℃ and the holding time was 3 to 6 hours.