共查询到19条相似文献，搜索用时 156 毫秒
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低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1 200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1 500～1 800℃降低到1 200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。 相似文献
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高纯碳酸锶是一种高附加价值的重要锶化合物,由于它具有独特的物理化学性能,因而被广泛应用于电子、化工、材料等领域。但高纯碳酸锶的生产仍存在环境污染严重、产品质量难以稳定控制、生产成本高等问题。综述了国内外高纯碳酸锶清洁生产工艺研究与应用进展,详细介绍了天青石碳还原法、天青石复分解法、粗碳酸锶酸溶碱析法、粗碳酸锶焙烧分解法、硝酸锶法、氯化锶法等高纯碳酸锶主要生产工艺的研究与应用进展,评述了各生产工艺产生的污染物的净化处理方法与技术改进,剖析了各工艺的优点和存在的问题。结合我国目前高纯碳酸锶的生产现状及与国外生产技术存在的差距,并对我国高纯碳酸锶生产技术的发展方向进行了展望。 相似文献
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中国盐湖卤水镁资源的开发形势十分严峻。首先是量大,仅青海盐湖集团提钾副产的镁卤量就超过中国海盐副产镁卤总量的3倍;其二是缺少适合开发的大宗镁产品,受中国镁碳酸盐矿物开发的冲击,世界范围内,以海湖卤镁为原料的炼镁企业和氧化镁厂商都逐渐退出行业竞争。镁碳酸盐矿物方面,菱镁矿主要生产镁质耐火材料,中国镁质耐火材料产量和产能居世界首位,且已开始变强并良性发展;白云石主要生产金属镁材料,中国金属镁产量和产能占世界的比例更大,也正努力做强;与另两大类镁质材料形成鲜明对比,镁质化工材料领域的现状是又小又弱,相关发展取决于能否率先将产品做成系列和规模。中国盐湖卤水镁资源过多甚至成为"镁害",但该资源价廉、含杂质少,是镁质化工材料的优质原料,应该在相关领域加大投入。 相似文献
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应用氯化镁—石灰乳法制备高纯氧化镁,降低氧化镁中钙含量是保证氧化镁产品质量的关键。通过对氧化镁的常温水化及二次煅烧,有效降低了氧化镁中钙含量,并通过正交试验得到了最优的水化工艺参数。氢氧化镁经850℃煅烧120 min,然后水洗,再次在1 050℃煅烧120 min,所得氧化镁纯度为99.1%99.4%,水化后钙含量(以CaO计)降低了约1%。 相似文献
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在我国乡镇企业发达的乡村地区,由于产业结构的调整和农业的自我服务化,形成了三种选择机制,影响农业区位,使自然地理过渡带优势逐步丧失,农业区位转移,农业区位质量也下降。建议制定宏观农业区位政策。 相似文献
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The continuing use of petrochemicals in mineral nitrogen(N) production may be affected by supply or cost issues and climate agreements.Without mineral N,a larger area of cropland is required to produce the same amount of food,impacting biodiversity.Alternative N sources include solar and wind to power the Haber-Bosch process,and the organic options such as green manures,marine algae and aquatic azolla.Solar power was the most land-efficient renewable source of N,with using a tenth as much land as wind energy,and at least 100 th as much land as organic sources of N.In this paper,we developed a decision tree to locate these different sources of N at a global scale,or the first time taking into account their spatial footprint and the impact on terrestrial biodiversity while avoiding impact on albedo and cropland,based on global resource and impact datasets.This produced relatively few areas suitable for solar power in the western Americas,central southern Africa,eastern Asia and southern Australia,with areas most suited to wind at more extreme latitudes.Only about 2% of existing solar power stations are in very suitable locations.In regions such as coastal north Africa and central Asia where solar power is less accessible due to lack of farm income,green manures could be used,however,due to their very large spatial footprint only a small area of low productivity and low biodiversity was suitable for this option.Europe in particular faces challenges because it has access to a relatively small area which is suitable for solar or wind power.If we are to make informed decisions about the sourcing of alternative N supplies in the future,and our energy supply more generally,a decision-making mechanism is needed to take global considerations into account in regional land-use planning. 相似文献
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The continuing use of petrochemicals in mineral nitrogen (N) production may be affected by supply or cost issues and climate agreements. Without mineral N, a larger area of cropland is required to produce the same amount of food, impacting biodiversity. Alternative N sources include solar and wind to power the Haber-Bosch process, and the organic options such as green manures, marine algae and aquatic azolla. Solar power was the most land-efficient renewable source of N, with using a tenth as much land as wind energy, and at least 100th as much land as organic sources of N. In this paper, we developed a decision tree to locate these different sources of N at a global scale, or the first time taking into account their spatial footprint and the impact on terrestrial biodiversity while avoiding impact on albedo and cropland, based on global resource and impact datasets. This produced relatively few areas suitable for solar power in the western Americas, central southern Africa, eastern Asia and southern Australia, with areas most suited to wind at more extreme latitudes. Only about 2% of existing solar power stations are in very suitable locations. In regions such as coastal north Africa and central Asia where solar power is less accessible due to lack of farm income, green manures could be used, however, due to their very large spatial footprint only a small area of low productivity and low biodiversity was suitable for this option. Europe in particular faces challenges because it has access to a relatively small area which is suitable for solar or wind power. If we are to make informed decisions about the sourcing of alternative N supplies in the future, and our energy supply more generally, a decision-making mechanism is needed to take global considerations into account in regional land-use planning. 相似文献
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