GTSP重钙工艺减少反应料浆含水量的初步研究

1 引言 我国耕地严重缺磷的面积所占比例高达2/3,而目前施肥的磷/氮比例又远远低于国际平均水平,如此的比例失调将严重影响农业增产.在当前施用的磷肥中,普钙和重钙占了很大的比例.由于重钙是用磷酸而非硫酸酸解磷矿,所以不含硫酸钙杂质,有效五氧化二磷的含量也由16～21%提高到45～52%,肥效比普钙提高两到三倍.为此国家"八五"重点项目引进了Hy dro GTSP工艺2×40万吨/年重钙装置.该装置于1999年3月试车以来难以达到满负荷生产. 作者通过对生产工艺各环节的分析,指出反应料浆含水量偏高是影响装置生产负荷的主要因素.料浆中水分的重要来源之一是二次球磨.     

贵州瓮福地区磷尾矿中钙、镁、磷的赋存状态测定

应用化学组分分析、X射线衍射分析、扫描电子显微镜及X射线能谱法等多种方法对贵州省瓮福地区磷尾矿中钙、镁及磷的赋存状态作了分析和研究。结果表明:①选自该矿区的磷尾矿为高镁(wMgO17.26%～17.65%),高钙(wCaO34.11%～34.56%),低磷(wP2O55.30%～5.69%)的固体矿物;②尾矿中镁主要以白云石形式存在,并有少量以磷酸盐和硅酸盐形式存在;钙主要也以白云石形式存在,加上少量以方解石和磷酸盐形式存在;磷主要以磷灰石形式存在,有少量存在于铁氧化物及独居石、磷钇矿中。     

Direct determination of total mercury in phosphate rock using alkaline fusion digestion

The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, this instrument underestimates Hg concentrations when phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473.     

The insoluble part of phosphorus fertilizers,obtained by processing of phosphorites of central kyzylkum with partially ammoniated extraction phosphoric acid

It is shown in the article that using ammophosphate treatment technology with poor in phosphorus highly carbonized ordinary phosphorite flour, washed dried concentrate, dust-like fraction, and mineralized phosphorite mass of Central Kyzylkum, it is possible to prepare concentrated phosphorus fertilizers of prolonged effect with the high content of assimilable form of P₂O₅.     

Diagnostics of the Behavior of apatite and its aggregates with sphene in dilute mineral acids

Behavior of monomineral fractions of apatite and sphene and their aggregates in treatment with dilute solutions of hydrochloric and sulfuric acids was studied by electron microscopy, IR spectroscopy, crystal-optical methods, and X-ray and chemical analyses. The manner in which aggregates of apatite and sphene disintegrate was for the first time visualized by electron scanning microscopy. The efficiency of purification of the apatite concentrate to remove apatite with hydrochloric and sulfuric acid solutions was examined.     

Recovery of lanthanides from extraction phosphoric acid produced by the dihydrate process

Variant of precipitation of a concentrate of lanthanides from the extraction phosphoric acid formed in the dihydrate processing of the Khibiny apatite concentrate by introduction of sulfuric acid and sodium compounds into the acid is suggested. The main components of the concentrate are double sulfides of lanthanides with sodium, calcium sulfate dihydrate, and sodium hexafluorosilicate. The efficiency of recovery of lanthanides into the concentrate was studied in relation to a sodium compound used.     

Sorption extraction of lanthanides from phosphoric acid solutions

The possibility of sorption extraction of lanthanides from nitric-phosphoric and phosphoric acid solutions with inorganic sorbents based on hydrated titanyl hydrophosphate was studied. New technological solutions were suggested for lanthanide sorption from the products which are formed in processing of the Khibiny apatite concentrate on mineral fertilizers (frozen nitric-phosphoric acid extract, a product of nitric acid decomposition of apatite, and the production phosphoric acid from the dihydrate process).     

Textural and structural characteristics of phosphorites from the Polpinsky deposit

The textural and structural characteristics of phosphorites from the Polpinsky deposit have been determined. These raw materials are shown to be of siliceous polymineral type and consist mostly of α-quartz, hydroxycarbonate apatite, montmorillonite, and bonschtedtite. The modification dynamics of chemical composition and the textural characteristics (specific surface, pore volume, and pore diameter) of the solid upon the acid decomposition of a phosphorite sample from Polpinsky deposit have been studied. The α-quartz in phosphorites is shown to not experience crystal-structural alterations upon acid decomposition; its pore size does not inhibit the extraction of acid-soluble components, including calcium and phosphorus, from the bulk.     

Thermal analysis of mechanoactivated mixtures of tunisia phosphorite and ammonium sulfate

The thermal behavior of Tunisia phosphorite and ammonium sulfate mixtures are examined by non-isothermal thermogravimetry in air atmosphere. It has been shown that the thermal stability of mixtures have different behavior after mechano-chemical treatment due to phase changes in the mixtures. New solid phases are confirmed by the stages and rate of mass changes and also by the heat effects observed. New phases are also confirmed by using X-ray diffraction method. Based on the data obtained by the mechanism of chemical transformations is proposed. The kinetics of mechano-activated mixtures decomposition is significantly influenced by the time of treatment and proceeds in few stages. Stage I is attributed to the effect of partially ammonia releasing, when the next stages are associated with the decomposition of apatite structures. Because of the interfacial interactions during mechano-chemical treatment insoluble phosphorous forms from apatite structures are transformed to the soluble forms suitable for plants nutrition. The results have shown that the soluble form can be controlled by the initial components ratio and conditions of treatment on the way to obtain slow releasing nutrition products. This revised version was published online in July 2006 with corrections to the Cover Date.     

Activation of leaching of rare earth elements from phosphohemihydrate

Treatment of fresh phosphohemihydrate obtained in processing the Khibiny apatite concentrate by hemihydrate sulfuric acid method was suggested by solutions containing alkali metal fluorides. It was shown that such treatment reduces the transit time of low-hydrated rare earth elements phosphates contained therein, which are poorly soluble in mineral acids, into the acid form from 2 months to 4–8 h.     

A study of the sulfuric acid leaching of rare-earth elements,phosphorus, and alkali metals from phosphodihydrate

The leaching of rare-earth elements, phosphorus, and alkali metals from phosphodihydrate, obtained in processing of the Khibiny apatite concentrate into mineral fertilizers, with sulfate solutions with a sulfuric acid concentration c(H₂SO₄) = 0.5−4 wt % was studied.     

Leaching of Lanthanides from Phosphohemihydrate with Nitric Acid

Factors were examined that determine passing of lanthanides into solution during nitric acid leaching of phosphohemihydrate obtained in the course of production of wet-process phosphoric acid from Khibiny apatite concentrate by the hemihydrate technique. The data obtained were compared to the results of sulfuric acid leaching.     

On sorption extraction of rare-earth elements in the nitric acid processing of Khibiny apatite concentrate

Fundamental aspects of the sorption recovery of rare-earth elements with a sulfocationite from a nitric-phosphoric acid solution formed as intermediate product in the nitric acid processing of Khibiny apatite concentrate were studied. It was confirmed that rare-earth elements can be effectively sorbed from a nitric-phosphoric acid solution without its preliminary neutralization. It was found that polyvalent metals can be sorbed from a nitric-phosphoric acid solution in the form of positively charged (possibly, single-charged) complexes containing nitrate and(or) phosphate ligands.     

Thermal behavior and phase transformations of nanosized carbonate apatite (Syria)

The phase transformations of Syrian phosphorite upon mechanochemical activation are examined in the present work. The latter is carried out in planetary mill equipped with 20 mm steel milling bodies and duration from 30 to 300 min. The established by means of DTA, DTG, TG analyses transformation of non-activated carbonate fluorine apatite type B into the carbonate hydroxyl fluorine apatite (COHFAp) mixed type A2-B leads to substantial changes in the properties of the activated samples expressed in lowering the degree of crystallinity, strong defectiveness of the structure, and increase of the citric solubility. The thermal analysis gives evidence for the decomposition of the carbonate-containing component within the phosphorite, as from the positions placed in the vicinity of the hexagonal 6₃ axis (type A2), as well as from the positions of the phosphate ion (type B), and from the free carbonates. The data from the thermal analysis, the powder X-ray analysis and the infrared spectroscopy give also evidence for phase transformations of the activated apatite (with admixtures of quartz and calcite) into Ca₁₀FOH(PO₄)₆, β-Ca₃(PO₄)₂, Ca₄P₂O₉, Ca₃(PO₄)₂ · Ca₂SiO₄ and for that one of the quartz—into larnite and wollastonite. The influence of the α-quartz as a concomitant mineral is considered to be positive. The α-quartz forms Si–O–Si–OH bonds retaining humidity in the solid phase thus facilitating the isomorphous substitution OH^? → F^? with the subsequent formation of partially substituted COHFAp. Calcium silicophosphate and Ca₄P₂O₉ are obtained upon its further heating. The presented here results settle a perspective route for processing of low-grade phosphate raw materials by means of tribothermal treatment aiming at preparation of condensed phosphates suitable for application as slowly acting fertilizer components.     

Toxicology problems at sulfuric acid technology of processing natural phosphates at producing mineral fertilizers and salts for technological application

The article contains data on the content of trace contaminant of cadmium compounds in phosphate ores of volcanic and sedimentary origin. On the basis of the data of laboratory and industrial studies with participation of the authors analyzed distribution of cadmium compounds at the processing apatite concentrate of Kolskii peninsula and Maroc phosphorites. It is shown that the toxic contaminants are mostly extracted with phosphoric acid and contaminates its and products of its further processing. The most advantageous from the toxicology viewpoint is appatite concentrate of Kolskii peninsula that contaminated minimally as compared with the phosphates originated at other birthplaces.     

New approach to processing of the apatite concentrate

New approach to processing of the apatite concentrate is suggested and substantiated. The approach includes treatment of the concentrate with a phosphoric acid solution at room temperature in the presence of a sulfo cation exchanger in the NH₄⁺ or H⁺ form. The phosphoric acid solution and the sorbent saturated with metal cations are separated and processed into target products by the known methods. The advantages and disadvantages of the approach are discussed.     

Separation of rare-earth elements and thorium in sorption conversion of phosphate rare-earth concentrate produced in nitric acid processing of Khibiny apatite concentrate

It is shown that REEs and thorium can be separated directly in the course of a sorption conversion of the phosphate rare-earth concentrate precipitated in nitric acid processing of the Khibiny apatite concentrate by introduction of compounds containing fluoride ions into the nitric acid solution used in the process. Under the optimal conditions, REEs are quantitatively adsorbed by the sulfo cation exchanger, whereas thorium mostly remains together with phosphorus and fluorine in the mother pulp. The influence exerted by the composition of compounds containing fluoride ions and process conditions on the separation efficiency of REEs and thorium. The suggested approach rules out formation of burial-requiring radioactive wastes with increased content of thorium.     

Thermal transformations in phosphorites

The thermal transformations in phosphorites during flash calcination were investigated by FT-IR spectroscopy, X-ray diffraction and chemical analyses. During flash calcination changes occur, both in the composition of the phosphorite and in the crystallochemistry of the fluor-carbonate-apatite (francolite). The former changes include: decomposition of a great part of the calcite in the rock and oxidation of organic matter. The latter changes include: partial removal of the structural carbonate; partial relocation of the remaining carbonate ions in the apatite structure; a new arrangement of hydroxyl groups and fluorine on the hexagonal axis; partial condensation of the orthophosphate groups and increase of crystallite sizes. Isomorphous substitution of PO ₄ ^–3 in apatite by SO ₄ ^–2 and SiO ₄ ^–4 may take place.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThe financial support from Rotem-Amfert-Negev Phosphate Co. is gratefully acknowledged. We thank Dr. B. Pregerson of the Rotem-Amfert-Negev for supplying samples     

Thermal investigations on phase transformations of Syrian phosphorite: Part I

The phase transformations of Syrian phosphorite upon mechanochemical activation are examined in the present work. The latter is carried out in planetary mill equipped with 20 mm steel milling bodies and duration from 30 to 300 min. The established by means of DTA, DTG, TG analyses transformation of non-activated carbonate fluorine apatite type B into the carbonate hydroxyl fluorine apatite (COHFAp) mixed type A2-B leads to substantial changes in the properties of the activated samples expressed in lowering the degree of crystallinity, strong defectiveness of the structure, and increase of the citric solubility. The thermal analysis gives evidence for the decomposition of the carbonate-containing component within the phosphorite, as from the positions placed in the vicinity of the hexagonal 6₃ axis (type A2), as well as from the positions of the phosphate ion (type B), and from the free carbonates. The data from the thermal analysis, the powder X-ray analysis and the infrared spectroscopy give also evidence for phase transformations of the activated apatite (with admixtures of quartz and calcite) into Ca₁₀FOH(PO₄)₆, β-Ca₃(PO₄)₂, Ca₄P₂O₉, Ca₃(PO₄)₂ · Ca₂SiO₄ and for that one of the quartz—into larnite and wollastonite. The influence of the α-quartz as a concomitant mineral is considered to be positive. The α-quartz forms Si–O–Si–OH bonds retaining humidity in the solid phase thus facilitating the isomorphous substitution OH⁻ → F⁻ with the subsequent formation of partially substituted COHFAp. Calcium silicophosphate and Ca₄P₂O₉ are obtained upon its further heating. The presented here results settle a perspective route for processing of low-grade phosphate raw materials by means of tribothermal treatment aiming at preparation of condensed phosphates suitable for application as slowly acting fertilizer components.     

高镁磷尾矿中钙、镁、磷赋存状态研究

选择了贵州省重要磷矿生产基地—瓮福磷矿浮选尾矿为代表,对其中钙、镁、磷的矿物学重要特征进行了比较系统的研究,获得了一些重要结论,从而为高镁磷尾矿的综合利用、白云石与胶磷矿的分离等提供理论依据,对实现磷尾矿资源的二次利用、指导开发者设计科学合理的矿石选冶工艺流程都有十分重要的意义。按照元素赋存形态分析的方法,选用了化学成分、化学物相、电子能谱、扫描电子显微镜、X射线粉晶衍射分析方法等多种手段系统、全面地测定了磷尾矿结构、形貌的重要特征,获得了钙、镁、磷赋存状态的重要结论,发现了尾矿及其原矿的异同性:磷尾矿中含量最高的组分及其含量分别是:氧化钙34.11%,氧化镁17.65%,五氧化二磷5.30%;镁主要以白云石的形式赋存,并有少量以磷酸盐、硅酸盐形式存在,其在各相占的比例分别为99.80%、0.10%、0.10%;磷主要以磷灰石的形式赋存(占97.08%),并有少量以铁氧化物(1.04%)、独居石(0.19%)、磷钇矿(1.83%)形式存在;钙主要以白云石的形式赋存(占96.95%),并有少量以方解石(1.11%)、磷酸盐(1.94%)形式存在。贵州瓮福地区高镁磷尾矿中的镁、磷、钙主要赋存形式分别为白云石、磷灰石、白云石。