钾长石-磷酸钙-石墨体系提取钾的实验研究

文中研究了钾长石-磷酸钙-石墨体系焙烧提取钾的工艺,通过助熔剂焙烧-水洗浸出-钾盐结晶分离工艺提高钾的提取率。在热力学分析的基础上,考察了还原剂用量、焙烧温度、钙硅摩尔比、助熔剂加入量对钾挥发率和浸出率的影响。结果表明,当m(富钾板岩)∶m(磷酸钙)∶m(石墨)=3.2∶1∶0.9、助熔剂氯化钙的加入量为钾长石质量的40%、反应温度为1350℃、焙烧时间为2 h时,钾的提取率超过95%,且磷酸钙中大部分的磷被还原,该工艺具有良好的工业应用前景。

添加NaCl-CaCO_3混合助剂焙烧难溶性钾矿提取氯化钾的实验研究

为综合利用我国难溶性钾矿提取氯化钾,采用石盐和石灰石作为焙烧难溶性钾矿的混合助剂,研究了钠钾摩尔比、石灰石加入量、焙烧温度与时间、钾钠挥发等因素对钾提取率的影响。钠钾摩尔比为4,石灰石加入量为12.5wt%的配料在900℃焙烧90 min的条件下,混合助剂实现了钾提取率84.6%。通过X射线衍射仪(XRD)对焙烧产物水浸后的滤渣进行了矿物组成分析,探讨了NaCl和CaCO_3作为混合助剂分解钾长石的机理。石盐和石灰石组成的混合助剂与难溶性钾矿的质量比为0.73,与其它体系相比,助剂用量大大降低。

草鱼鱼油钾法提取及其脂肪酸组成分析

采用响应面法优化钾法提取草鱼加工废弃物中鱼油的工艺,并运用气相色谱对其脂肪酸组成进行分析。在单因素实验的基础上,选择pH、水解时间、水解温度、盐用量作为实验因素,利用Box-Benhnken设计和响应面分析法,通过回归分析确定最佳提取工艺为:pH 9.2,水解时间43min,水解温度58℃,盐用量9.5%,在此工艺条件下鱼油提取率达58.61%。气相色谱分析结果表明,草鱼鱼油中饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸的含量分别为22.63%-26.07%、45.09%-47.93%、25.99%-31.32%。

富钾页岩的高压水热化法提取钾研究

实验主要研究了利用高压水热法在助剂作用下富钾页岩的提钾过程。确定的最佳反应条件为以CaO为助剂、C/S(钙硅摩尔比)=2.0、浸出时间4h、浸出温度250℃、原料粒度-0.074mm含量90%以上、搅拌速度1000r/min和液固比11.4。试验结果表明最佳的浸出率可以达到95%以上。用XRD进行了物相分析,并初步分析了在高压水热条件下钾长石提钾的主要反应机理。

贵州省钾长石提钾工艺初步研究

在高温条件下,利用熔融浸渍法,对贵州万山地区钾长石进行提钾工艺研究,全面探讨助熔剂的阴离子及阳离子对钾提取率的影响,最终选定NaCl为最佳助熔剂。正交实验数据表明,钾长石提钾的较佳工艺条件为:焙烧温度900℃、焙烧时间120 min、m(钾长石)∶m(NaCl)=1.5,钾的提取率为87.97%。

阴离子对熔盐浸取法从钾长石中提钾的影响

研究采用熔盐浸取法从钾长石中提取钾的工艺,分别选用不同阴离子的钙盐,比较出选择不同助熔剂时其阴离子对钾长石中钾溶出率的影响,确定了最佳助熔剂为CaC l2。

西南地区主要类型土壤钾素有效性分析

通过测定西南地区主要类型土壤的基本农化性状、Q/I曲线、固钾率和酸提取钾来研究土壤钾素缓冲容量(PBCK),进而分析土壤钾素的有效性。试验结果表明,PBCK与土壤CEC、固钾率和酸提取均呈极显著正相关,因此可以用KPBC来衡量土壤钾素有效性。

杂卤石溶解动力学

杂卤石中含丰富的钾资源 ,由于其化学上的难溶性和埋藏较深 ,尚未合理开发利用 .已有研究表明 ,杂卤石矿层具备溶浸开采的地质基本条件 .矿石中钾的溶解是杂卤石资源合理利用的技术关键 .利用CaCl2 水溶液为溶剂 ,通过测定溶浸液中钾、钙离子的浓度 ,考察了溶浸剂浓度、矿石粒度、温度对杂卤石表观溶解动力学过程的影响 .实验条件下 ,矿石中钾的溶解率随粒度的降低明显升高 .矿石粒度在 0 1 4 9～ 1mm之间 ,钾的溶解率可达 80 %以上 .该溶解反应为一级反应 (对CaCl2 而言 ) .计算实验条件下溶浸过程表观动力学速率常数 ,得溶解反应表观活化能为 8 34kJ·mol-1 ,实验结果初步表明杂卤石溶解过程受内扩散控制 ,溶解动力学方程符合未反应核收缩模型 。

Potassium recovery from muscovite using NaCl-roasting followed by H_(2)SO_(4)-leaching

The present study aims at the recovery of potassium from muscovite mica(which contains K_(2)O;~10 wt%)using NaCl-roasting coupled with H_(2)SO_(4)-leaching process.The preliminary acid leaching studies applying different mineral acids resulted in a potassium recovery of 8%−18%.The optimum leaching conditions for the maximum recovery were 4 mol/L H_(2)SO_(4),60 min leaching time and liquid-solid ratio 4 mL/g at 90℃.However,the roasting of muscovite with additive NaCl(muscovite:NaCl mass ratio of 1:1.00,900℃,45 min)followed by H_(2)SO_(4)-leaching(95℃,60 min)extracted potassium to the tune of 98%.Under similar roasting conditions,the H_(2)O-leaching process extracted only 60%of potassium.The effects of various roasting and leaching parameters such as temperature,time,NaCl concentration,acid concentration,liquid-solid ratio on potassium extraction were evaluated.The appearance of the sylvite(KCl)mineral phase in the NaCl-roasted muscovite and its disappearance in the acid/water leached residue confirmed the physical and chemical distortions of the muscovite crystal structure.The possible mechanism of potassium release from the complex muscovite structure was elucidated based on available literature substantiated by characterizations using X-ray diffraction(XRD)and scanning electron microscopy with energy dispersive X-rays spectroscopy(SEM-EDX).

Kinetic study on selective extraction of HCl and H_3PO_4 in a microfluidic device

In the extraction method for preparing KH2PO4, one of the key processes is the selective extraction of HCI over H3PO4. In our work, extraction kinetic studies have been carried out in a microfluidic device with a coaxial microchannel, using the extractant of 33.3% （by volume） trioctylamine （TOA） dissolved in n-octanol, with differ- ent aqueous phases： the HCI solution, the H3P04 solution, and H3PO4 and KCI solutions of different concentra- tions. The changes of the extraction efficiency of HC1 and H3P04 and the selectivity for HC1 along with the residence time were investigated. We found that fast extraction kinetics could be realized in microfluidic devices, and that HC1 could be extracted faster than H3P04 due to smaller mass transfer resistance and much stronger re- action between HCI and TOA. For the extraction of H3PO4 and KC1 solutions, the selectivity for HC1 first increased and then decreased when TOA was in excess of H3PO4 in the initial feeds, and in contrast, always increased when H3PO4 was in excess of TOA in the initial feeds. The diverse changes of selectivity for HCI along with the residence time indicate that a dynamic control of selectivity in microfluidic devices may be important and accessible for im- proving the KH2P04 conversion efficiency in extraction method.

钾法提取淡水鱼内脏鱼油的工艺

以淡水鱼内脏为原料,采用钾法提取其中的鱼油,以鱼油得率为指标,考察pH、温度、液固比、水解时间、盐用量和盐析时间对鱼油得率的影响。通过单因素试验和正交试验,得到钾法提取内脏鱼油的最佳工艺:溶液的p H 7,液固比1.25∶1(mL/g),水解温度60℃,水解时间30 min,盐析时间40 min,盐用量5%(1 g),在此条件下所得到的鱼油得率为39.5%。该研究为淡水鱼下脚料的开发利用提供了理论研究基础。

Extraction of potassium from K-feldspar via the CaCl_2 calcination route

The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl.As much as approximately 41% of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91% in 40 min, while the extraction was reduced to only 22% at the theoretical mass ratio of 0.2. Optimal process conditions are as follows: ore particle size of 50–75 μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min.The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the conversion reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.

Application of Kinetic Models in Describing Soil Potassium Release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

Potassium （K） release characteristics in soil play a significant role in supplying available K. Information on K-release characteristics in soils of central Iran is limited. The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran. The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L-1 CaC12 in a period of 2-2017 h at 25±1℃. Soil K was extracted by distilled water, 0.5 mol L-1 MgNO3, 0.002 mol L-1 SrC12, 0.1 mol L-1 BaC12, 0.01 mol L-1 CaC12, 1 mol L-1 NaC1, 1 mol L-1 boiling HNO3, 1 mol L-1 NH4OAC, Mehlich 1, 0.002 mol L-1 SrC12 ＋ 0.05 mol L-1 citric acid, and ammonium bicarbonate-diethylenetriamine pentaacetic acid （AB-DTPA）. A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h. Thus, two equations were applied to two segments of the total reaction time （2-168 and 168-2 017 h）. Cumulative amounts of K released ranged from 55 to 299 mg kg-1 in 2-168 h and from 44 to 119 mg kg-1 in 168-2 017 h. Release kinetics of K in the two time segments conformed fairly well to parabolic diffusion, simplified Elovich, and power function models. There was a wide variation in the K release rate constants. Increasingly higher average concentrations of soil K were extracted by distilled water, Mehlich 1, SrC12, CaC12, SrC12 ＋ citric acid, AB-DTPA, MgNO3, NaCI, NH4OAc, BaCI2, and HNO3. Potassium release rate constants were significantly correlated with K extracted. The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.

Can Nonexchangeable Potassium be Differentiated from Structural Potassium in Soils？

Nonexchangeable K （NEK） is the major portion of the reserve of available K in soil and a primary factor in determining soil K fertility. The questions of how much NEK is in soils and how to quantify total NEK in soils are so far still unclear due to the complicated effects of various minerals on K fixation. In this study, the NEK in 9 soils was extracted with sodium tetraphenylboron （NaBPh4） for various time periods longer than 1 d. The results showed that the NEK extracted by NaBPh4 gradually increased with time, but showed no more increase after the duration of extraction exceeded 10 20 d. As the temperature increased from 25 to 45 ~C, the duration to obtain the maximum extraction of NEK was reduced from 20 to 10 d, and the maximum values of NEK released at both temperatures was almost the same for each soil. The maximum NEK （MNEK） of the 9 soils extracted by NaBPh4 varied from 3074 to 10081 mg kg-1, accounting for 21% 56% of the total soil K. There was no significant correlation between MNEK released by NaBPh4 and other forms of K, such as NH4OAc-extracted K, HNO3-extracted K and total K in soils, which indicates that NEK is a special form of K that has no inevitable relationship to the other forms of K in soils. The MNEK extraction by NaBPh4 in this study indicated that the total NEK in the soils could be differentiated from soil structural K and quantified with the modified NaBPh4 method. The high MNEK in soils made NEK much more important in the role of the plant-available K pool. How to fraetionate NEK into different fractions and establish the methods to quantify each NEK fraction according to their bioavailability is of great importance for future research.

A Device for Simulating Soil Nutrient Extraction and Plant Uptake

In situ evaluating the availability of soil nutrients has been a challenge. In this study, a new type of Device for Simulating Soil Nutrient Extraction and Plant Uptake （DSSNEPU） and its operating procedures were introduced. The device consists of a sampling tube, a fluid supply system, a low pressure system, a tube sheath and an elution cylinder. The sampling tube was firstly soaked in the solution of 0.5 mol L-1 NaHCO3 and then buried into soils. The fluid supply system was connected to the sampling tube and the deionized water was supplied. During the period, low pressure system started a vacuum for 3 min every 10 rain interval. After extraction, the sampling tube was removed and the nutrients on the sampling tube were eluted with 0.5 tool L-1 HCl. The elution solution was used for nutrient measurement. The amounts of P and K extracted by DSSNEPU reached the maximal values after 4 h. No significant increases of P and K were observed for longer extraction duration. The optimal temperature for extracting P and K was 30 ℃ in this experiment. Extracted P and K were increased by 83.3% and 84.6% with the employment of low pressure system in comparison to those without employing low pressure system. Correlation analysis indicated that 1~ and K extracted by DSSNEPU were highly correlated with those by conventional chemical extraction and by plant uptake. The above results suggest that this device is applicable to assess the availability of nutrients in soils.

Simultaneous Extraction of Phosphorus, Potassium, Calcium and Magnesium from Soils and Potassium Recommendations for Crops in Southern Brazil

Simultaneous multi-element extraction has been increasing worldwide to improve soil laboratory testing quality and efficiency. This study sought to investigate the applicability of the Mehlich-1, Mehlich-3, and resin methods for simultaneous extraction of soil available P, K, Ca, and Mg as well as the effect of using conversion equations on nutrient recommendations for crops. Topsoil （0-20 cm） samples were taken from the most representative soil types used for crop production in southern Brazil with a wide range of chemical, physical, and mineralogical properties. Soil P, K, Ca, and Mg were simultaneously extracted using 1.0 mol L-1 KCl, Mehlich-1 and Mehlich-3 solutions, and membrane resin. The amounts of P extracted with the Mehlich-1 method were, on average, 50% lower than those extracted with the resin and Mehlich-3 methods. However, the resin method extracted the lowest amounts of K, Ca, and Mg. The use of conversion equations was suitable and it did not affect negatively the K recommendations for crops grown on soils of southern Brazil.