红河磷肥厂半水-二水物法磷酸装置生产小结

半水－二水物磷酸工艺（Ｎｏｒｓｋ－Ｈｙｄｒｏ流程）矿耗低、酸浓高、动力消耗少,但操作控制较复杂、对磷矿的质量要求高、半水物磷酸系统的腐蚀性较强。红河磷肥厂反复摸索、整改,使６０ｋｔ／ａ半水－二水物法磷酸装置的月产量稳定在５０００～５５００ｔ（Ｐ２Ｏ５计）,各项工艺指标已基本达到设计要求。介绍混合矿中主要组分对生产的影响,半水物和二水物磷酸系统的工艺控制范围,磷石膏结晶形态发生转变时的处理方法,设备     

湛江化工厂OXY半水物磷酸工艺评述

阐述了适合中国国情的半水物法磷酸的设计模式,并详细分析对比了半水物法与二水物法磷酸生产水平衡和热平衡的特点,特别指出采用干法排渣工艺时延长带式过滤机使用寿命所采取的对策。     

浅析磷矿杂质对二水物法湿法磷酸生产的影响

本文论述了磷矿中主要杂质对二水物法湿法磷酸生产中浓度、过滤强度、比重及粘度等的影响。     

红河州磷肥厂半水—二水物法磷酸装置设计和生产小结

介绍了该装置的工艺设计和试生产、整改的主要情况,并对其在国内推广应用提出了一些看法。该装置是我国引进Norsk-Hydro半水-二水物磷酸工艺技术的第一套。该工艺具有直接生产高浓度磷酸,矿、能耗低以及磷石膏中磷、氟等杂质含量低,便于综合利用等特点。该装置1993年5月建成投产,经两年多试生产和几次整改,于1995年9月8日～11日进行了72小时性能考核,考核结果各项指标接近或达到设计要求。     

二水法磷酸改半水-二水法或二水-半水法工艺路线 探讨

针对二水法磷酸杂质含量高、过滤酸浓度低、副产磷石膏质量差等缺点,提出将其技改为半水-二水法磷酸、二水-半水法磷酸。分析半水-二水法磷酸、二水-半水法磷酸工艺优缺点,介绍改造内容及方案,并进行工艺比较。二水-半水法适合只考虑磷石膏资源化利用、企业自有硫酸副产蒸汽配套的企业,半水-二水法适合磷酸用于制造高端磷化工产品的企业。     

新型半水物湿法磷酸工艺流程

在四川大学洁净石膏发明专利技术基础上,开发出了具有自主知识产权的新型半水物湿法磷酸工艺流程,并成功实现工业化应用.该流程继承了半水物流程的优点,并实现磷石膏的提纯和高效利用,可充分利用中低品位磷矿生产湿法磷酸;节省磷酸生产的原材料及能耗;产品磷酸浓度和质量提高;副产磷石膏品质好,可代替天然优质石膏用于开发高附加值产品,...     

第四讲 二水物流程

第四讲二水物流程吴佩芝（上海化工研究院）１概述硫酸分解磷矿制湿法磷酸时，控制硫酸钙二水物（ＣａＳＯ＿４·２Ｈ＿２Ｏ）结晶形式的工艺流程称为二水物流程，反应如下：反应后的料浆中含有磷酸溶液、石膏固相和未被分解的含磷矿物。液、固相一般用过滤和洗涤的方法分...     

湿法萃取磷酸中高效搅拌装置的研究,开发及应用

介绍在半水物湿法磷酸工艺开发过程中,根据水力学模型试验研究结果,研制了带导流筒的高效搅拌装置,为半水物硫酸钙结晶营造了最佳水力学条件,并为双槽结晶中的核心设备溶解槽和结晶槽提供了工程设计参数。该技术已成功地应用于昆明化肥厂１．５ 万吨／年双槽半水物工程,使我国半水物湿法磷酸的技术开发进入了实用阶段,实现了工业化。在此基础上又开发了二水物湿法磷酸的单槽单桨反应器,在全国获得了迅速的推广应用     

比利时普莱昂厂二水-半水磷酸技术及磷石膏直接利用介绍

生产湿法磷酸副产的磷石膏综合利用途径多,国内外都很重视并在继续推广。介绍Central-Prayon二水-半水生产湿法磷酸的工艺技术特点、主要操作参数、运行数据和该工艺对多种磷矿的适应性,以及半水磷石膏用石灰乳中和,自然水化为二水石膏的质量指标,因其游离水含量仅(6～10)％,可代替天然石膏使用。     

黄铁矿对二水物法制湿法磷酸的影响

针对湖南洗溪磷矿重介质选精矿含黄铁矿较多这一情况，研究了黄铁矿对该矿采用二水物法制湿法磷酸的影响，阐明了用重介质选精矿制湿法磷酸能获得较好经济技术指标的原因，提出了合理评价重介质选精矿质量的建议。     

Polymerization of acrylamide in the presence of calcium sulfate dihydrate and calcium sulfate hemihydrate

The homopolymerization of acrylamide in water alone and also in the presence of calcium sulfate dihydrate and of calcium sulfate hemihydrate has been studied. Polymerizing acrylamide with the redox pair potassium persulfate—sodium bisulfite, the rate increased steadily with increasing initiator concentration. In the presence of up to 25% dihydrate, the rate was like that of acrylamide alone. However, when adding the “reactive” hemihydrate that is hydrated to the dihydrate concurrently with the progressing polymerization, the rate is somewhat slower in comparison with the two other systems. For determination of the compositions of the various reaction products, a method combining DTA and XRD data has been developed.     

Assessment of propionic acid adsorption performance on the phase transformation of calcium sulfate hemihydrate to dihydrate

The adsorption of propionic acid during the transformation process of calcium sulfate hemihydrate to calcium sulfate dihydrate was studied in a batch-type crystallizer with respect to contact time, additive concentration and temperature in pure media, and in the presence of propionic acid used as an additive. The adsorbent was characterized by X-ray diffraction, scanning electron microscopy and thermogravimetric analysis combined with a Fourier-transform infrared spectrometer and a mass spectrometer. The adsorption characteristics were also investigated by means of evaluating the isotherm, kinetic and thermodynamic properties. The results of this investigation showed that propionic acid can serve as a good accelerator for the transformation process from calcium sulfate hemihydrate to dihydrate.     

Impact of glutamic acid on the transformation of calcium sulfate hemihydrate to dihydrate: Characterization,equilibrium, kinetics,and thermodynamics

In this study, the characteristics and mechanisms of glutamic acid adsorption on the transformation process of calcium sulfate hemihydrate to calcium sulfate dihydrate were investigated in a batch-type crystallizer. The phase transformation was followed by conductivity measurements in both the absence and the presence of glutamic acid used as additive. The structure of the samples obtained during this process was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, thermogravimetric analyzer-mass spectrometer, and ATR-FTIR analyses. From the results, it was shown that the uptake of glutamic acid caused a retarding effect in the transformation rate. It was also found that the thin- and weak-layered structure was replaced by a thick and compact plate-like structure. The adsorption isotherms, kinetics, and thermodynamics were also explored to describe the process. According to the results, the Langmuir isotherm model fit quite well, as demonstrated by the high R² value, calculated using a linear and nonlinear procedure, and the maximum adsorption amount of 169.49?mg/g. The pseudo-first-order and pseudo-second-order kinetic models were applied to analyze the kinetic experimental data, and it was determined that the adsorption of glutamic acid followed the pseudo-second-order model, which indicates that the adsorption rate depended on chemisorption. The thermodynamic results illustrated that the adsorption of glutamic acid in the transformation process was spontaneous and endothermic.     

Preparation of calcium sulfate dihydrate and calcium sulfate hemihydrate with controllable crystal morphology by using ethanol additive

Calcium sulfate hemihydrate (CSH) with controlled crystal morphology has attracted broad interests due to its superior physical and chemical properties, as well as excellent biological performance. In this study, calcium sulfate dehydrate (CSD) was firstly synthesized via the reaction of H₂SO₄ and Ca(OH)₂ using ethanol as morphology modifier. The prepared CSD was then converted to CSH through a hydrothermal method. It was found that the precipitation time of CSD powders was dramatically shortened and the morphology of CSD crystals was changed from thick tabular to short-rod with the increment in ethanol addition. The finally-obtained CSH crystals were found to have hexagonal prisms shape with smaller aspect ratios. The CSH powder with the desired crystal morphology would provide improved setting behavior and biological performance of the CSH bone cement.     

Observations on calcium sulphate dihydrate formed in media rich in phosphoric acid. II. Derived calcium sulphate hemihydrate

A study was made of the properties of calcium sulphate hemihydrate prepared by the calcination of dihydrate formed in a medium containing finally 29·4% P₂O₅ and 5·6% H₂SO₄. When the original dihydrate had been precipitated in uncontaminated acid, hydration of the hemihydrate seemed to be normal. However, when the medium of precipitation contained hydrofluoric acid and salts of iron and aluminium, the calcination product was not susceptible to a retarder that markedly affected the hydration of commercial calcined gypsum. The presence of P₂O₅ did not appear to be responsible for this type of defect. The bulk volume and water requirement seemed to be normal when the crystal forms of the component grains were normal. Observations are made on the strengths of the derived cast gypsum.     

The reactivity of calcium sulphate hemihydrate

Studies were made of the effects of temperature, duration of heating and intergranular movement during the dehydration of gypsum in vacuo, on the reactivity of the resultant calcium sulphate hemihydrate. The formation of orthorhombic anhydrite was not associated with a significant increase in reactivity. The results are discussed in terms of variations in the population of seeding nuclei for the growth of gypsum. The kinetics of the formation of orthorhombic anhydrite from soluble anhydrite formed from gypsum in vacuo are significantly different from those found when soluble anhydrite has been formed by dehydrating calcium sulphate hemihydrate.     

The hydration of calcium sulphate hemihydrate

The isothermal kinetics of calcium sulphate hemihydrate hydration have been determined (i) by thermogravimetry and microcalorimetry for water vapour hydration and (ii) by microcalorimetry for liquid water hydration. The dehydration conditions of gypsum modify the reactivity of the obtained product. Only gypsum dehydrated in a vacuum or in a very low water pressure is likely to rehydrate. The mechanism “Le Chatelier” would not be only one to apply during hydration with liquid water.     

工业级二水合磷酸二氢钠含量测定方法的研究

提出了用电位法测定工业二水合磷酸二氢钠含量.电位法是利用校准过的酸度计,用氢氧化钠标准溶液滴定至试样溶液pH为9.3.并且采用重量法、中和法与电位法进行比对.结果表明,用电位法测定工业二水合磷酸二氢钠含量操作简单、快捷、准确,且稳定性好.     

Kinetics of hydration of autoclaved calcium sulphate hemihydrate

The kinetics of the hydration of two sources of autoclaved calcium sulphate hemihydrate have been followed by an essentially isothermal method. Experiments have been carried out at different temperatures, water/powder ratios, and with added nuclei of crystallisation. A kinetic equation, based on the Avrami theory of crystallisation, and assuming the reaction to be diffusion-controlled, has been developed and tested and found to be moderately successful under most conditions. The effects of variations of temperature and water/powder ratio are discussed.     

Thermoluminescence and reactivity of calcium sulphate hemihydrate

The influence of methods of preparation of calcium sulphate hemihydrate on its rehydration kinetics is studied using thermoluminescence. The different treatments modify the number of traps. There exists a relation between the concentration of a defect in the calcium sulphate hemihydrate and the parameters of the hydration kinetics, measured by calorimetry. The obtained differences cannot be related to the variation of specigic surface.