Calcination of phosphates: reactivity of calcined phosphate

Detailed investigations of the effect of physical, chemical and mineralogical changes in calcined phosphate rocks on its chemical reactivity were carried out. It was found that the presence of CaCO₃ and/ or CaO decreases the chemical reactivity of phosphates by consuming the active reagent in the reactivity test. Transformation of carbonate apatite to the less reactive fluorapatite species is another reason for lower reactivity of calcined phosphates. Finally, crystal growth and crystal annealing at higher temperatures lead to less reactive material after calcination.     

试生产篦冷机压床事故的处理

我公司3200t／d生产线采用3．2m×27m液压传动（二段）充气梁篦冷机,设计产量为4000t／d,液压传动压力最大25MPa,初始设定为18MPa,篦板最大行程为140mm,初始设定为110mm,设定最大篦速为20次／min。试生产过程中连续出现2次篦冷机压床事故,后经调整问题得到解决。     

Modelling of a biomass fired furnace for production of lime

This paper deals with the mathematical modelling of a furnace devoted to the limestone processing. The novelty of this reactor is that the energy required by the endothermic reaction of calcination is provided by the combustion of biomass, making it compatible with sustainable development. The model is based on balance equations completed with phenomenological relations for the estimation of heat and mass transfer inside the reactor and for the estimation of the kinetics of the reaction. In a first section, the equations describing the behaviour of a single reacting particle of limestone are derived. The model relies on the assumption that the reacting particle obeys the shrinking core model. Then this model of a single particle is introduced in a more general one-dimensional model describing the whole furnace, where the different relevant properties depend upon the location within the reactor. Some industrial information is compared to numerical predictions, thus validating the model. Also the results provided by the numerical model allow for a better comprehension of the different phenomena occurring within the reactor.     

Zn-Al水滑石及其焙烧产物对水中磷的吸附研究

用水热法制备了不同尿素浓度下的Zn-Al水滑石,焙烧后制得焙烧态水滑石,用XRD、SEM 、BET、FTIR等方法对样品进行了表征,考察了水滑石及焙烧产物对水中磷酸盐的吸附性能.结果表明:水滑石对磷酸盐的吸附基本符合假二级动力学方程和Langmuir吸附等温式,当尿素浓度为0.6 mol/L,150℃水热24h,300...     

THL—1型煤气炉高效炉箅的研制及应用

1　3 .6m煤气炉原扇形炉箅存在的问题我厂造气车间 3 .6m煤气发生炉是 5 0年代由前苏联引进的 ,煤气炉采用扇形炉箅。它承担着空气和蒸汽入炉后均匀分布、支撑料层、下吹煤气通过、灰渣的破碎与排除的任务 ,为煤气炉操作实现高炉温、好透气、好床层、长周期服务。煤气发生炉原使用的炉箅是由扇形面和梯形面各五块加上大底座组成的。扇形面从上至下 ,从左到右都有坡度 ,梯形面从上至下水平排列 ,由于整体坡度不大 ,加上炉箅转动很慢 ,下部料层蠕动幅度很小 ,导致破渣不力 ,是原炉箅的一大缺陷。炉温过高结渣后 ,渣块掉到炉箅下沿 ,靠炉箅…     

Semicoke production from long-flame coal in a rotary furnace

Rotary-drum technology for semicoke production from Shubarkol??sk long-flame coal is outlined. The properties of semicoke for use as a reducing agent in ferroalloy production are presented.     

Mineralogical and morphological changes of calcined paper sludge at different temperatures and retention in furnace

This work reports the project of thermal effects in mineralogy and texture of the paper sludge to employ them as pozzolanic material.For this reason, the chemistry and mineralogical composition has been studied, as well as its morphology by XRD, SEM and EDX.The initial sludge has been treated to 700, 750 and 800 °C during 2 and 5 h being observed that initial kaolinite becomes metakaolinite and that its pozzolanic activity with a paper sludge treated to 700 °C for 2 h is comparable to that of a commercial metakaolinite. The transformation of kaolinite after the dehydroxylation is to convert in amorphous metakaolinite. At the temperature mentioned above, calcite from the initial sludge is maintained active.It is concluded that the pozzolanic activity of metakaolinite is strongly related to the crystallinity of the original kaolinite. Well-ordered kaolinite is transformed into more reactive metakaolinite.     

Evaluation of two rock phosphates and a calcined rock phosphate as maintenance fertilizers for crop — pasture rotations in Western Australia

Two long-term (11 and 12 y) field experiments in south-western Australia are described that measured the relative effectiveness of three rock phosphate fertilizers (C-grade ore, Calciphos and Queensland (Duchess) rock phosphate), single, double and triple superphosphate. The experiments were on established subterranean clover (Trifolium subterraneum) — based pasture that had received large, yearly, applications of single superphosphate for many years before the experiments began so that in the first year the nil phosphorus (P) treatment produced 80 to 90% of the maximum yield. The experiments were conducted using a rotation of one year cereal crop (oats,Avena sativa at one site, and barley,Hordeum vulgare, at the other): 2 y pasture, a typical rotation on farms in the region. Five levels of each P fertilizer were applied every third year with the crop. Grain yield of cereals, P content of grain, pasture yield, and bicarbonate-soluble P extracted from the soil (available P) were used to estimate fertilizer effectiveness values.The three superphosphate fertilizers had identical values of fertilizer effectiveness. Superphosphate was always the most effective fertilizer for producing grain. The rock phosphate fertilizers were one-seventh to one-half as effective per kg P as superphosphate when assessed on the yield or P content (P concentration × yield) of grain within each cropping year. Bicarbonate-extractable soil P values demonstrated that superphosphate was two to fifteen times as effective as the rock phosphate fertilizers. The relationship between grain yield and P content in grain (i.e. the internal efficiency of P use curve) was similar for the different P fertilizers. Thus for all P fertilizers yield was not limited by other factors as it varied solely in response to the P content, which in turn presumably depended on the P supply from the fertilizers.The relative agronomic effectiveness of rock phosphates is greater for marginally P deficient soils than for highly P deficient soils but rock phosphate remains less effective than superphosphate. We conclude that the rock phosphates studied should not be substituted for superphosphate as maintenance fertilizers for soils in Western Australia that are marginally deficient in P. This result is consistent with the results of many field experiments on highly P deficient soils in south-western Australia. These have shown that a wide variety of rock phosphate fertilizers are much less effective than superphosphate in both the short and long term.     

篦冷机篦下压力瞬间波动的原因分析

<正>我公司现有两条2500t/d预分解窑生产线,篦冷机都是采用的第三代充气梁篦冷机,投产后运行比较正常,冷却效果良好,但1号熟料生产线的篦     

矿粉脱氟法生产饲料级磷酸氢钙主要工艺指标控制

根据连云港新磷矿化有限责任公司所用磷矿的特点,探讨矿粉脱氟法生产饲料级磷酸氢钙工艺过程中脱氟、萃取、中和3个关键岗位工艺指标的控制.选择适合的工艺控制指标,取得了良好的效果,与传统二段中和法比,硫酸、石灰消耗明显减少,P205回收率提高15％～20％.     

浅谈IKN篦冷机篦板速度的控制

第三代篦冷机活动篦床的高温区段保持尽可能小的篦板间隙非常重要。高压风从篦板的倾斜喷嘴喷出，在沿篦板上表面迅速扩散开后，大部分应上升进入熟料层，在完成热交换后，进入篦床的上部空间。     

尾气循环流化氨化制备粒状磷铵过程分析与现场试验

针对磷铵生产过程高含湿尾气排放量大的特点,首次提出了尾气循环流化氨化制备粒状磷铵新工艺,研究了高含湿气体条件下喷雾流化、氨化反应、结晶干燥一体化工艺过程.工艺计算结果表明,尾气循环条件下系统热效率达59.52%,比传统干燥技术提高约1倍.设计建成了千吨级中试装置,并在现场运行条件下考察了系统的放大规律和操作弹性,为该技术的产业化开发和推广奠定了基础.     

磷铵尾气减排与节能的过程分析与实验

分析了60万吨/年磷酸二铵（DAP）生产装置尾气形成“磷铵雨”的热力学机理,提出尾气部分冷凝- 磷酸降膜蒸发过程耦合技术,现场实验证明了该技术的可行性,现场实验获得的P₂O₅质量分数27.1%～41.7%范围内磷酸蒸发浓缩数据,该工艺使尾气湿含量减少至0.065 kg H₂O/kg air。研究了磷酸液膜雷诺数以及磷酸液膜过冷度对磷酸降膜蒸发过程的影响,揭示了在55℃以下低温浓缩湿法磷酸的可能性。这对磷酸浓缩技术很有参考价值。     

Hydraulic operation of a glass furnace and its role in production

Translated from Steklo i Keramika, No. 5, pp. 8–11, May, 1993.     

“水泥窑+炉排炉”协同处置生活垃圾技术的研究及应用

首先介绍了炉排炉结构和工作原理,分析了水泥窑+炉排炉协同处置生活垃圾技术的工艺流程,并同其他几种水泥窑协同处置生活垃圾技术相对比。最后,介绍了该技术在水泥厂改造项目的应用情况,并对炉排炉的运行,炉渣、熟料特性以及项目投入产出进行了分析。     

副产蒸汽氯化氢合成炉在氯碱生产中的应用

介绍了新疆天业集团天辰化工有限公司应用副产蒸汽合成炉的应用情况及效果。     

浅析硫酸钾曼海姆反应炉的国产化

硫酸分解氯化钾是生产Ｋ２ＳＯ４的主要方法,国际上具有代表性的为比利时的ＴＥＳＳＥＲＤＥＬＯＣＨＩＭＥ公司法、日本窒息法、日产法及台湾青上法,均采用曼海姆护法。目前国内硫酸钾生产约６０％采用台湾青上曼海姆反应炉。其原理： ２ＫＣＩ＋Ｈ２ＳＯ４－Ｋ２ＳＯ４＋２ＨＣｌ 随着国内硫酸钾生产的日趋饱和,面对日趋严峻的市场,只有降低生产成本才能取得竞争优势。然而曼海姆反应炉每１８个月要进行一次中修,每３年需进行一次大修,且曼海姆炉为引进设备,其进口配件价格昂贵。苏州精细化工集团公司是最早引进曼海姆炉的厂家之一…