磷石膏和钾长石制硫酸钾的试验研究

萃取磷酸生产中副产的大量固体废弃物磷石膏已成为制约磷复肥工业发展的重要因素.针对我国可溶性钾矿资源严重匮乏,而钾长石储量丰富,指出了利用磷石膏与钾长石生产硫酸钾具有现实意义.试验研究了 KAlSi3O8—CaSO4—CaCO3体系的配料比、焙烧温度、焙烧时间、助剂、焙烧样粒度对焙烧产物中 K2O收率的影响,确定了在 n(KAlSi3O8)∶n(CaSO4)∶n(CaCO3)=2∶1∶6配料比下,最适宜的工艺条件为:焙烧温度1000℃、焙烧时间2.0h、助剂 Na2SO4用量为反应物料总量的7%,焙烧产物粒度为74~84μm(180~200目),钾长石中 K2O收率达90%以上.     

Influence of time and temperature on reactions and transformations of muscovite mica

Abstract

Members of the mica group of clay minerals are important constituents of clays used as raw materials for the production of bricks, tiles, and clay pipes. Using muscovite, K₂ Al₄ (Si₆ Al₂ )O₂₀ (OH)₄ ), as the pure end member representative of the mica group, their thermal behaviour has been determined and is expressed as a time–temperature–transformation (TTT) diagram. Water loss occurs over a prolonged temperature range with no discrete event resulting in significant weight loss. The thermal decomposition of muscovite is dominated by the presence initially of the three sheet types which make up the layered mica structure. Initially γ-Al₂O₃ and then corundum form from the octahedrally co-ordinated aluminous sheet which is sandwiched by two tetrahedral sheets. With potassium from the interlayer site, the tetrahedral sheets break down to form a melt, from which leucite crystallises. Topotactic influences of this type account for the failure of muscovite to produce potassium feldspar and mullite as predicted by the equilibrium phase diagram for the system K₂O–Al₂O₃–SiO₂.     

钾长石-氧化钙-氢氧化钾体系提钾工艺研究

采用球磨反应和静态水热反应对钾长石-氧化钙-氢氧化钾体系提钾工艺进行了研究,结果显示：温度对钾长石提钾有较大的影响,静态水热反应提钾效果优于球磨反应.较适宜的静态水热反应工艺条件为：m（氧化钙）/m（钾长石）为1.5,m（钾长石）/m（氢氧化钾）为15,恒温220℃下反应10h,每克钾长石加水量为20 mL,此时钾溶出率达到90％以上.     

Adsorption and Reactivity of CO2 on Potassium-Covered Re(001)

The interaction of CO₂ with potassium-covered Re(001) has been investigated. This system has been studied by means of work function (Δϕ), optical second harmonic generation (SHG), and temperature-programmed desorption (TPD) measurements. Strong electronic interaction between carbon dioxide and potassium is observed upon adsorption at 90 K. This is indicated by a rapid quenching of the SHG signal of K following postadsorption of CO₂, with a quenching cross section of 70 Ų. Work function change measurements are consistent with such interaction, evidenced by an undepolarization effect, namely, further decrease of the work function upon CO₂ adsorption, below the minimum obtained by pure potassium. In the presence of potassium, the dissociation probability of 0.5 ML adsorbed carbon dioxide increases from 0.5 on the clean metal surface to 0.85 on 1 ML potassium-covered Re(001), information obtained from TPD measurements following heating to 1250 K. It is concluded that a K–CO₂ surface compound is formed upon adsorption at 95 K on the potassium-covered surface.     

Structure property relations of copolymerised polypropylene /SiO2 nanocomposites prepared by solid state shear milling (S3M) method

Abstract

In the present paper, solid state shear milling (S³M) method was used to prepare the copolymerised polypropylene (Co-PP)/nano-SiO₂ composites under the conditions of solvent free and non-organic treatment. The change of phase morphology and arrangement of SiO₂ under mechanical force were firstly observed in the complex multiphase and multicomponent Co-PP/nano-SiO₂ composite. The effect of milling cycles on the phase structure and mechanical properties was studied. It was found that the S³M method was an effective way which can adjust the phase structure of composite through change of milling cycles. After 20 milling cycles, the composite can form a structure with a lot of SiO₂ particles around the ethylene–propylene copolymer phase, the Charpy notched impact strength of the composite with 4 wt-%SiO₂ particles can be largely improved from 24·2 to 38·2 kJ m^–2. While after 30 milling cycles, the composite can form a structure with SiO₂ particles dispersed more uniformly in the Co-PP matrix. However, with this structure, the prepared composite has higher stiffness but the notched impact strength could not be greatly improved. The mechanism of the toughening effect is discussed and the structure property relation established.     

Enrichment of 41K isotope in potassium formed on and in a rhenium electrode during plasma electrolysis in K2CO3/H2O and K2CO3/D2O solutions

It was found that potassium forms on rhenium electrodes during plasma electrolysis in K₂CO₃/H₂O and K₂CO₃/D₂O solutions, and the new potassium has unnatural isotopic ratios. The isotope ⁴¹K increases from the natural abundance, 6.7%, to as much as 32–37%. The percentage of ⁴¹K in the potassium contamination in a rhenium electrode before electrolysis was close to the natural isotopic abundance (6.7%). This result suggests that the ⁴¹K was enriched by some unknown process connected with a vigorous discharge of plasma electrolysis.     

Preparation and performance study of cordierite/mullite composite ceramics for solar thermal energy storage

The employment of solar energy in recent years has reached a remarkable edge. It has become even more popular as the cost of fossil fuel continues to rise. Energy storage system improves an adjustability and marketability of solar thermal and allowing it to produce electricity in demand. This study attempted to prepare cordierite/mullite composite ceramics used as solar thermal storage material from calcined bauxite, talcum, soda feldspar, potassium feldspar, quartz, and mullite. The thermal physical performances were evaluated and characterized by XRD, SEM, EPMA, and EDS. It was found that the optimum sintering temperature was 1280°C for preparing, and the corresponding water adsorption was 11.25%, apparent porosity was 23.59%, bulk density was 2.10 mg·cm^?3, bending strength was 88.52 MPa. The residual bending strength of specimen sintered at 1280°C after thermal shock of 30 times decreased to be 57 MPa that was 36% lower than that before. The thermal conductivity of samples sintered at 1280°C was tested to be 2.20 W·(m·K)^?1 (26°C), and after wrapped a PCM (phase change materials) of K₂SO₄, the thermal storage density was 933 kJ·kg^?1 with the temperature difference (ΔT) ranged in 0‐800°C. The prepared cordierite/mullite composite ceramic was proved to be a promising material for solar thermal energy storage.     

亚熔盐分解钾长石矿样中钾铝硅的分离

采用KOH亚熔盐法常压低温分解河北钾长石矿粉,回收过量碱后,用硫酸溶解固渣,得含高浓度钾、铝、硅的母液;采用溶胶?凝胶法和分步醇析法从母液中制备硅凝胶、钾明矾和硫酸钾,钾明矾热解制备氧化铝. 结果表明,钾长石矿中各组分含量分别为K2O 13.13wt%,Al2O3 16.66wt%,SiO2 58.28wt%. 在H+浓度3.80 mol/L及95℃条件下母液易形成硅凝胶,脱硅率达98%以上,SiO2含量大于99.0%,比表面积大于700 m2/g,孔容约为1.0 cm3/g,孔径为5?6 nm;对脱硅母液分步醇析,在25℃、醇料体积比为1时,优先析出钾明矾,铝析出率达98%,降温至5℃并增大醇料体积比至2,可从母液中结晶析出硫酸钾,钾回收率达89%.     

Determination of the Optimum Conditions for Copper Leaching from Chalcopyrite Concentrate Ore Using Taguchi Method

The optimum conditions for the extraction of copper from chalcopyrite concentrate into SO₂-saturated water were evaluated using the Taguchi optimization method. High level copper recovery was obtained in an environmentally friendly process that avoids sulfur dioxide emission into the atmosphere because SO₂ forming in the roasting is used in the dissolution. Experimental parameters and their ranges were chosen as follows: reaction temperature, 293–333 K; solid-to-liquid ratio, 0.025–0.15 g/mL; roasting time, 30–90 min; roasting temperature, 773–973 K; stirring speed, 400–800 rpm; and reaction time, 10–60 min. The particle size and gas flow rate were 63 µm and 10 cm³/min, respectively. The optimum conditions of the dissolution process were determined to be reaction temperature of 318 K, a solid-to-liquid ratio of 0.025 g mL^?1, a roasting time of 75 min, a roasting temperature of 773 K, a stirring speed of 400 rpm, and a reaction time of 30 min. Under optimum conditions, dissolution yield of copper was 91%.     

Preliminary investigations on alkali leaching kinetics of red sediment ilmenite slag

The present paper deals with soda ash roasting of red sediment ilmenite (47.03% TiO₂) and leaching of obtained titanium rich slag with hydrochloric acid for preparation of synthetic rutile. The experimental conditions used for roasting are Na₂CO₃ to ilmenite ratio of 1: 1 at 1,223 K for 4 h. This soda ash slag product is subjected to hydrochloric acid leaching to remove the iron content. The optimum conditions for leaching achieved are 6M hydrochloric acid at 398 K for 2.5 h (10/1 liquid/solid mass ratio) at 100 rpm. Shrinking core model is found to be fit for the experimental results. The apparent activation energy is 37.9 kJ/mol. This process of soda ash roasting is one of the best processes for preparation of high purity synthetic rutile assaying about 97.21% TiO₂.     

降温煅烧活化钾肥的研制及肥效试验

针对钾长石高温煅烧能耗高的问题,在900°C下加入复方活化剂对钾长石进行降温煅烧,并对制得的活性钾肥肥效进行玉米盆栽试验和大田试验验证。结果显示,活化钾肥产品的水溶性钾含量明显提升,较未活化前增加26倍;在钾养分减少45%的条件下,活化钾肥的肥效与氯化钾相当,其淋溶钾损失减少,作物吸钾量提高。活化钾肥是实现"减量增效"的新型肥料。     

Investigation on possibility of mechanochemical synthesis of CaTiO3 from different precursors

Recently, mechanochemical synthesis was widely used in preparation of perovskite type of materials, such as BaTiO₃, PbTiO₃, PZT, etc. In this work, the possibility of mechanochemical synthesis of CaTiO₃ from different precursors, such as CaCO₃ or CaO and TiO₂ was investigated. Intensive milling of mixture of CaO and TiO₂, under optimal milling conditions, resulted in synthesis of single phase CaTiO₃. It was also found that intensive milling of powder mixture containing CaCO₃ and TiO₂ only activate the powders for the sintering process; hence the CaTiO₃ could be obtained at lower temperatures of sintering. To complete reaction of CaTiO₃ formation during milling it is necessary to reduce CO₂ partial pressure, i.e. it is necessary to change the atmosphere inside the vials during milling. In this work, an explanation for difference in milling behavior of different precursors was proposed and discussed.     

Glass-ceramics from a zinc-electroplating solid waste: Devitrification promoted further crystallization of parent glass upon heat treatment

A solid waste from a zinc electroplating production line was successfully used as a main raw material for synthesizing glass-ceramics with a fine microstructure. X-ray fluorescence spectroscopy analysis on dried solid waste shows that the waste mainly contains iron and zinc oxides. X-ray diffraction (XRD) analysis identifies Fe₃O₄ and ZnO phases in calcined waste samples. Based on the above results, silica sand, lime stone and potassium feldspar were proportionally added to make parent glasses by melting the batches at 1450?°C for 2?h. The as-synthesized products show typical DSC and thermal expansion curves with obvious glass transition phenomenon. However, XRD patterns reveal that they had devitrified to form ZnFe₂O₄ phase during the shaping and cooling of the melts. The devitrification became weaker when more potassium feldspar was added. It is interesting to find that the pre-crystallization of ZnFe₂O₄ in the devitrified sample was beneficial to its further crystallization during the following heat-treatment. The result implies that the devitrification of parent glasses is not necessarily a detriment to the preparation of glass-ceramics via controlled crystallization process.     

硅石焙烧-酸浸提纯及杂质相结构的演变

在硅石提纯过程中,采用XRD和EDS分析硅石中杂质元素赋存特征,采用高温焙烧活化与酸浸复合提纯方法研究了酸浸过程杂质相结构演变及提纯效果. 结果表明,硅石中不同类型铝硅酸盐的K, Na, Ca, Al, Si含量不同,主要分为长石类、伊利石和高岭石;酸浸提纯过程中硅石的杂质相不仅会溶解在酸中,且长石类杂质相会演变成伊利石和高岭石. 与未预酸浸的硅石提纯相比,预酸浸的硅石经高温焙烧活化提纯后纯度达99.995%,达到高纯石英砂的纯度,杂质Al和K含量分别降低了76.6%和66.5%;在700℃下焙烧,预酸浸硅石的Al和K去除效果最好,去除率分别为85%和41%.     

Nanoparticles of a New Potassium(I) Coordination Polymer from Thermal Treatment with Oleic Acid: Syntheses, Characterization, Thermal, Structural and Solution Studies

Nanoparticles of a new potassium two-dimensional coordination polymer, {[K₂(μ₄-L)₂(μ-H₂O)₄]_n·nH₂O} (1), HL = 3-{[(4-nitrophenyl)methylen]amino}benzoic acid} were synthesized from thermal treatment of compound 1 with oleic acid at 523 K. The nanoparticles were characterized by scanning electron microscopy and FT-IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction. The crystal structure of this compound indicates that the coordination number for the potassium ions is seven. A hydrogen bonding network and π-π stacking interactions result in more stability of compound 1 crystal packing. The thermal stability of compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The results of stoichiometry studies and formation of compound 1 in MeCN solution were found to be in support of its solid state stoichiometry and show the 1:1 complex formation between the L⁻ and K⁺ ion in MeCN solution.     

Additional high-energy milling to enhance the performance of porcelain stoneware manufacturing

Porcelain stoneware tile is the best class of ceramic tiles regarding technical performance. Low porosity and high glass content are some of its highlighted characteristics. The manufacturing cost is highly dependent on the feldspar content and the processing flow rate. Certain technical bottlenecks in the manufacturing steps, such as milling, forming, and firing, are intrinsically associated with limitations in the processing properties, such as the dry strength, bulk density, and pyroplastic deformation. In this work, improvements in these properties were achieved using high-energy milling (HEM) after conventional milling (CM). This study was carried out on a pilot industrial scale in the milling stage. Six experimental runs were evaluated. Slurries were spray-dried. The powders were humidified with 6.5% moisture. Specimens were conformed under a specific pressure of 45 MPa. The firing was performed using temperature ranging from 1150 to 1230°C. The use of HEM, in comparison to traditional milling for the similar particle-size distributions, has increased the dry density, +0.2 g.cm⁻³, dry bending strength, +1.0 MPa, and decreased the pyroplastic deformation index, −1.10⁻⁵ cm⁻¹. These results allow an estimated thickness reduction of 10%.     

Synthesis of MnFe2O4 nanocrystals by wet-milling under atmospheric conditions

This work reports an original method for synthesis of well-crystallized manganese ferrite (MnFe₂O₄) nanoparticles via a high energy wet milling technique under atmospheric conditions, starting from metallic Mn and Fe powders in the presence of distilled water. The effects of milling conditions on the formation and magnetic properties of MnFe₂O₄ nanoparticles were investigated in detail. Fully stoichiometric MnFe₂O₄ nanocrystals with an average crystallite size of 14.5 nm were produced after 24 h of milling. As-synthesized MnFe₂O₄ nanocrystals were found to show soft magnetic behavior at room temperature with saturation magnetization of 53 emu/g. Due to reduced thermal effects, the saturation magnetization increased to 68 emu/g at 5 K. Results show that this method is simple and efficient for the mass production of MnFe₂O₄ nanoparticles.     

Analysis of the milling rate of pharmaceutical powders using the Distinct Element Method (DEM)

The milling behaviour of microcrystalline cellulose (MCC) and α-lactose monohydrate (αLM) in an oscillatory single ball mill has been analysed by using the Distinct Element Method (DEM). The experimental results suggest that the milling behaviour of αLM is more strongly influenced by the milling frequency as compared to MCC. A similar conclusion is also drawn from the DEM results. The milling behaviour of MCC and αLM is described by a first order rate process, and its rate constant, K_p, is found to correlate very well with the milling power, P_n, determined by the DEM simulation, except for the milling behaviour of αLM at 18 Hz. For the latter, there appears to be an incubation time after which the milling rate increases substantially. The results presented here provide a basis for predicting the milling behaviour of a material systematically based on the fundamental material properties and the machine dynamics without the need for extensive experiment and use of large quantities of materials.     

Effect of processing parameters on the formation process of nano-sized ZrB2 powders by the high energy ball milling

ABSTRACT

Nano-sized ZrB₂ powders were synthesised using the high energy ball milling with ZrO₂ and B₂O₃ as raw materials and Mg as the reducing agent. The resulting powders were characterised by X-ray diffraction, scanning electron microscopy, laser particle size analysis, transmission electron microscopy, energy dispersive spectrometry, and X-ray photoelectron spectroscopy. The influence of the synthesis parameters, including the ratios of ZrO₂ to B₂O₃, milling medium, and reaction time, on the synthetic course of the ZrB₂ nanopowders were studied systematically. The mechanisms by which these parameters influence the synthetic course of and the resulting product quality are determined. Ultimately, the diameter of the resulting particles is about 200–400?nm, which are an agglomeration composed of many individual small particles with an average diameter of ～50?nm. In addition, the oxidation of ZrB₂ powders has also been studied.     

Correlation between potassium losses and mineral matter composition in catalytic coal steam gasification

The utilization of potassium as catalyst in coal steam gasification suffers due to difficulty in its quantitative recovery from gasification residues. This is due to the formation of non-leachable compounds with the mineral matter of coal. The reactivity of K₂CO₃ with some mineral constituents of coal has been evaluated at 973 K; after reaction, residues were analysed by XRD and leached with water to test the potassium solubility. Subsequently, through investigation of the interaction of potassium with 8 carbonaceous matrices from four differen ccoals, an attempt was made to establish a correlation between ash characteristics and quantity of non-recoverable potassium. It was also possible to identify some compounds formed by reaction between potassium and mineral matter.