Preparation of Calcium Lanthanum Sulfide Powders via Alkoxide Sulfurization

Calcium lanthanum sulfide powders were prepared by reacting methoxides of calcium and lanthanum with H₂S. Alkoxide mixtures of various La/Ca ratios dispersed in methanol were reacted with H₂S at 25° to 85°C and the amorphous gels obtained after the removal of methanol were heat-treated in H₂S for full sulfurization at various temperatures. Up to 500°C, cubic LaS₂ was the only crystalline phase present. Calcium lanthanum sulfide phase started to form at 550°C. In the temperature range of 650° to 750°C, single-phase calcium lanthanum sulfide powders were obtained for La/Ca = 2.41 and 2.68.     

提高氟硅酸钠得率的途径

分析湛化企业集团公司过磷酸钙生产副产氟硅酸钠得率低 (每吨过磷酸钙副产 5 .86 kg氟硅酸钠 )的原因 :由于过磷酸钙混化工艺及氟吸收工艺、设备存在的问题 ,造成氟的无组织排放 ,使氟硅酸产量低、浓度波动、质量差。通过混化均衡生产 ,增加氟硅酸澄清槽 ,更新氟硅酸钠离心式过滤机和结晶槽 ,严格生产管理 ,使氟硅酸钠得率提高到 6 .82 kg/ t。按 380 kt/ a SSP计 ,可增产氟硅酸钠 36 5 t/ a,增加效益 2 0万元 /年     

盐酸法生产饲料级磷酸氢钙新工艺研究

针对目前中国化工企业盐酸法饲料级磷酸氢钙生产工艺存在的弊端，系统地研究了“去渣一段中和”新工艺。实验结果表明：稀盐酸用量和浸取反应时间是影响磷矿石中磷及含氟杂质溶出率的关键因素，活性硅和氯化钠用量对产品质量有重要影响。通过实验数据分析处理得出实验条件下的最佳工艺条件：每30g磷矿粉加入稀盐酸（HCl质量分数≤20％）1200mL，浸取反应时间120min，活性二氧化硅（以SiO2计）用量1．0g，氯化钠用量2．0g.在此条件下，产品中磷收率达95％以上，氟的去除率达96％以上，产品质量超过HG2636-2000标准要求，生产成本下降。     

表面活性剂对超细碳酸钙的防团聚作用研究

超细碳酸钙由于粒径小，比表面积大，表面自由能高，在生产、贮存过程中极易发生团聚。在Ca（OH）2的低温搅拌碳化反应制备超细碳酸钙的过程中，对所得碳酸钙用表面活性剂处理，考察了阴、阳、非离子表面活性剂对超细碳酸钙的防团聚作用。结果表明：某些阴离子、非离子表面活性剂可有效地抑制碳酸钙晶粒的团聚，使制得的碳酸钙粉体的粒度小于1μm，且使其粒度分布明显变窄，而阳离子表面活性剂对防团聚则无明显作用。采用复配表面活性剂比单一表面活性剂更能有效地防止超细碳酸钙的团聚，使其团聚粒径明显降低，粒径分布明显变窄。     

苛化法制备亚微米纺锤形碳酸钙联产氢氧化钠

为了解决制碱白泥所带来的二次污染问题,在苛化法的基础上改进出一种新工艺。该工艺在制碱过程中不再副产白泥,而是将原料中的钙转化生成高附加值的亚微米纺锤形特种碳酸钙,并联产高含量的液体氢氧化钠。研究了消化与苛化工艺条件对碳酸钙粒径和氢氧化钠含量的影响,采用扫描电镜（SEM）对样品形貌做了表征。结果表明：在柠檬酸钠添加量为1%（质量分数）、消化水温为84 ℃、闷灰时间为40 min、加料时间为20 min的条件下,制备出颗粒短径为180 nm、粒径分布为150~200 nm、长径比为3的亚微米纺锤形碳酸钙,并联产出高含量的液体氢氧化钠。     

The initial and residual value for subterranean clover of phosphorus from crandallite rock phosphates,apatite rock phosphates and superphosphate

The residual value of phosphorus from superphosphate, crandallite rock phosphate (Christmas Island C-grade ore), 500°C calcined crandallite rock phosphate (Calciphos) and apatite rock phosphate from Queensland, Australia, was measured in a 6 year field experiment sited on lateritic soil in south-western Australia. Different amounts of each fertilizer were applied at the commencement of the experiment, and either left on the soil surface or mixed through the soil by cultivating to a depth of about 10 cm. Dry matter production of subterranean clover measured in spring (August) and bicarbonate-extractable phosphorus determined from soil samples collected in summer (January–February) were used as indicators of fertilizer effectiveness.The effectiveness values calculated for each fertilizer each year were similar for the treatments that were left on the soil surface and those which were mixed through the soil. The effectiveness of both ordinary and triple superphosphate were similar each year. They were the most effective fertilizers for the duration of the experiment. Using pasture yield as an indicator, the effectiveness of the superphosphates decreased by about 50% from year 1 to year 2, and by a further 10% over the remaining 4 years. Using bicarbonate-extracted soil phosphorus the effectiveness of both superphosphates decreased in a more uniform fashion by about 60% from year 2 to year 6. The effectiveness of all the rock phosphate fertilizers was approximately constant through time. As calculated from yield and bicarbonate-soluble phosphorus values, C-grade ore, Calciphos and the Queensland apatite were respectively 5%, 20% and 7% as effective as freshly applied superphosphate.The proportion of the total phosphorus content present in the rock phosphates which was initially soluble in neutral ammonium citrate was a poor predictor of the effectiveness of the phosphorus from these fertilizers determined using herbage yield or the amount of bicarbonate — soluble phosphorus extracted from the soil.The bicarbonate soil test did not predict the same future production for superphosphate and some of the rock phosphates in years 2 and 3 of the experiment, indicating that different soil test calibration curves are needed for the different fertilizers.     

组合式流化床中以高钙镁钛渣为原料制取TiCl4

This paper describes a new method for producing TiCl4 by chloridizing materials of high content CaO and MgO, in which a combined fluidized bed is used as a reactor to avoid agglomeration between particles caused by molten CaCl2 and MgCl2. The combined fluidized bed consists of at least a riser tube and a semi-circulating fluidized bed. Two kinds of high titanium slag, in which the total mass content of CaO and MgO is 2.03% and 9.09% respectively, are employed to examine the anti-agglomeration effect and the conversion of the materials when the temperature ranges are between 923.15K and 1073.15K, gas apparent velocity 0.7-1.1m·s-1, and inlet amount of solid materials is 4.6-7.0kg·h-1. It is found that the anti-agglomeration effect in the combined fluidized bed is satisfactory and the new method can achieve a TiCl4 production capacity of 14.0-75.4t·m-2·d-1 in relation to 25.0-40.0t·m-2·d-1 from the conventional bubble bed. Furthermore, low-temperature chloridization, for example, at 923K or 973K, can also be used to produce TiCl4 and avoid agglomeration.     

Direct Synthesis and Hydration of Calcium Aluminosulfate (Ca4Al6O16S)

Calcium aluminosulfate (Ca₄Al₆O₁₆S or C₄A₃̄) was prepared by direct synthesis from calcium and aluminum nitrates, and aluminum sulfate. CaAl₄O₇(CA₂) formed as an intermediate at 900°C, and C₄A₃̄ was the main phase after calcination at 1100°C. The specific surface areas after calcination at 1100° and 1300°C were ∼2.5 and 1 m²/g, respectively. Hydration was investigated using XRD, DSC, SEM, conduction calorimetry, and solid-state ²⁷Al MAS-NMR spectroscopy. Calorimetry showed that the induction period was longer than that of a sample prepared using conventional solid-state sintering, and this was attributed to the formation of amorphous coatings. Crystalline hydration products, principally calcium monoaluminosulfate hydrate and aluminum hydroxide, appeared subsequently. Although the induction period was very long, complete hydration occurred as early as 3 d in the sample calcined at 1100°C and was 91% complete in the sample calcined at 1300°C.     

Low-Temperature Synthesis of Calcium Hexa-Aluminate

Calcium hexa-aluminate (CaO·6Al₂O₃) has been prepared from calcium nitrate and aluminum sulfate solutions in the temperature range of 1000°–1400°C. A 0.3 mol/L solution of aluminum sulfate was prepared, and calcium nitrate was dissolved in it in a ratio that produced 6 mol of Al₂(SO₄)₃·16H₂O for each mole of Ca(NO₃)₂·4H₂O. It was dried over a hot magnetic stirrer at ∼70°C and fired at 1000°–1400°C for 30–360 min. The phases formed were determined by XRD. It was observed that CaO·Al₂O₃ and CaO·2Al₂O₃ were also formed as reaction intermediates in the reaction mix of CaO·6Al₂O₃. The kinetics of the formation of CaO·6Al₂O₃ have been studied using the phase-boundary-controlled equation 1 − (1 − x )^1/3= K log t and the Arrhenius plot. The activation energy for the low-temperature synthesis of CaO·6Al₂O₃ was 40 kJ/mol.     

水解连续化新工艺在双氰胺生产中的应用

针对国内间歇式水解和过滤工艺技术落后的局面，我厂经反复试验实现了水解连续化生产双氰胺的新工艺，从而使各项技术指标均达到和超过设计水平。