Extraction Of Potassium Research Articles

Desorption of Potassium and Magnesium by Gray Forest Soil

It has been shown that a long-term potassium deficiency in the agrocenosis reduces the ability of gray forest soil to desorb this element into the soil solution to a much greater extent than magnesium deficiency – magnesium desorption. It has been established that the mobility of potassium cations is greater than that of magnesium, regardless of the degree of soil depletion in relation to these elements: 0.1–0.5 M ammonium acetate solution extracted almost the entire soil stock of exchangeable potassium, whereas magnesium – only 65–90%. During fractional extraction of potassium with 0.001 M ammonium acetate solution, differences between soils with different potash content were noted only in the first 2–3 extracts; in the following extracts, the potassium content was equalized. The magnesium content in successive extracts decreased gradually and approximately equally in soils with its different initial content. It has been shown that the intensity and specificity of soil desorption of potassium and magnesium well reflects soil fertility in relation to these elements.

Salar de Atacama Lithium and Potassium Productive Process

The average lithium content in the Earth’s crust is estimated at about 0.007%. Despite this, lithium is considered abundant and widely distributed, with significant extraction from various sources. Notably, the brines in the Salar de Atacama are highlighted for their high lithium concentration ~1800 mg/L. Lithium is currently recovered from these brines through a solar evaporation process. The brine is transferred through a series of ponds, increasing the lithium concentration from 0.2% to 6% over 18 months, while decanting other minerals like potassium, magnesium, and boron. This method is the most efficient and cost-effective globally due to the Salar de Atacama’s high lithium concentration of approximately 1800 ppm and the region’s intense solar radiation, which facilitates evaporation at no economic cost. This manuscript describes in detail the lithium and potassium extraction processes used in the Salar de Atacama.

Preparation of high-purity magnesia spinel refractory raw materials with spinel-wrapped periclase structures using bischofite from salt lake

A large amount of bischofite is produced in the process of potassium extraction from salt lake, which seriously affects the ionic balance of brine system. In this study, a high-purity magnesia spinel refractory raw material with a spinel-wrapped periclase structure was directly prepared using bischofite by a precipitation-sintering approach. A coupling process of one-time crude magnesium chloride solution recrystallization and three-time precipitates washing was employed to remove crucial impurities (sodium, potassium, boron, etc.) and prepare the magnesium hydroxide precipitates with a high purity of 99.37 %. The lightly calcined magnesia gained from the high-purity magnesium hydroxide precipitates and white corundum were then employed for preparing the refractory raw materials. The effects of particle size and dosage of white corundum on the phase distribution, microstructure, and physical properties of the materials were thoroughly studied. The results illustrated that the prepared refractory raw materials were mainly composed of periclase and spinel phases, showing a distinct spinel-wrapped periclase structure that could enhance the physical properties. Therefore, the prepared refractory raw materials showed a high bulk density of 3.46 g·cm−3, a low apparent porosity of 2.46 %, and a linear shrinkage rate of 12.33 %, under the optimum conditions of white corundum particle size of 3.00 μm and alumina/magnesia mass ratio of 3:10.

Bespoke strategies of Paxillus involutus to extract potassium from diverse phyllosilicates

Phyllosilicates provide a primary source of minerals used by microorganisms and plants, particularly clay minerals, i.e., phyllosilicates of very small particle size. Fungi can actively break down (or “weather”) minerals to extract nutrients, but whether they use identical mechanisms when accessing different clay minerals is unclear. In addition, it is yet to be understood whether starvation stresses due to the limited availability of a mineral-nutrient would result in different weathering behaviours of microbes.Here, we performed a microcosm experiment to address these questions. We used the ectomycorrhizal basidiomycete Paxillus involutus and the phyllosilicates K-vermiculite, muscovite and phlogopite. These silicates have different degrees of recalcitrance to the removal of K cations from the mineral, and each was provided in the microscosm experiment as the sole potassium (K) source. The type of potassium "extraction-assimilation" was tested against a potassium-availability gradient, with a situation of maximum starvation stress (no potassium availability) and one of maximum availability (potassium provided as a solute in the culture medium). Our study revealed that different phyllosilicate minerals stimulated different patterns of fungal gene expression, which indicated bespoke weathering mechanisms for different phyllosilicates. The potassium uptake capacity of the fungus was highest with K-vermiculite compared to phlogopite and muscovite. Interestingly, the assimilation of phosphorus by the fungus was reduced in K-depleted conditions.Moreover, the potassium deprivation condition prompted the fungus to assimilate sodium instead. Also, in the presence of the minerals, the fungus showed significant differences in gene expression compared with the negative and positive control conditions, suggesting that the mineral environment modulates the starvation stress levels. The nutrients assimilated by the mycelium from both the minerals and the culture medium also varied according to the type of silicate added and the K starvation level to which the fungus was subjected. Based on what has been observed here, many geochemical processes could depend on fungi's genetic and functional plasticity, which would have considerable environmental consequences with a direct link between the evolution of fungi and that of the Earth's crust.

Evaluation of five soil nutrient extraction methods for practical assessment of phosphorus and potassium availability for tomato (<i>Solanum lycopersicum</i>) fertilization in Andisols-Garut, Indonesia

Phosphorus and potassium are essential nutrients for plant growth and development. Plants will achieve optimum biomass and production if phosphorus and potassium needs are met through fertilization. Determining the availability of phosphorus and potassium in the soil is essential because it is related to decisions on phosphorus and potassium fertilizer rate recommendations. In this study, we evaluated 5 common phosphorus and potassium extraction methods by correlating the indicated soil nutrient levels to the relative biomass dry weight of tomato plants. The phosphorus and potassium extraction methods used were Mehlich-1, Bray-1, Morgan-Wolf, Ammonium acetate, and HCl-25%. Mean Root Error (MRE) and Root Mean Square Error (RMSE) were used to determine the precision of the linear regression equation model in predicting the relationship between phosphorus and potassium soil extraction methods and the relative biomass dry weight of tomato plants. The correlation of the soil extraction methods used in Andisols with the relative biomass dry weight of tomato was highly significant and very strong (r > 0.75) suggesting that Bray-1 was the best soil-phosphorus extraction method (P<sub>r</sub> = 0.88; P<sub>MRE</sub> = 0.10; P<sub>RMSE</sub> = 4.44), while HCl-25% was the most suitable for soil-potassium extraction (K<sub>r</sub> = 0.90; K<sub>MRE</sub> = 0.05; K<sub>RMSE</sub> = 2.95). The results of the two extraction methods will be used to determine the dosage of phosphorus and potassium fertilizers (<i>nutrient sufficiency approach</i>) for tomato plants grown in Andisols.

Stepwise extraction of lithium and potassium and recovery of fluoride from aluminum electrolyte wastes through calcification roasting-two-stage leaching.

Aluminum electrolyte is a necessity for aluminum reduction cells; however, its stock is rising every year due to several factors, resulting in the accumulation of solid waste. Currently, it has become a favorable material for the resources of lithium, potassium, and fluoride. In this study, the calcification roasting-two-stage leaching process was introduced to extract lithium and potassium separately from aluminum electrolyte wastes, and the fluoride in the form of CaF2 was recycled. The separation behaviors of lithium and potassium under different conditions were investigated systematically. XRD and SEM-EDS were used to elucidate the phase evolution of the whole process. During calcification roasting-water leaching, the extraction efficiency of potassium was 98.7% under the most suitable roasting parameters, at which the lithium extraction efficiency was 6.6%. The mechanism analysis indicates that CaO combines with fluoride to form CaF2, while Li-containing and K-containing fluorides were transformed into water-insoluble LiAlO2 phase and water-soluble KAlO2 phase, respectively, thereby achieving the separation of two elements by water leaching. In the second acid-leaching stage, the extraction efficiency of lithium was 98.8% from water-leached residue under the most suitable leaching conditions, and CaF2 was obtained with a purity of 98.1%. The present process can provide an environmentally friendly and promising method to recycle aluminum electrolyte wastes and achieve resource utilization.

Scaly MoS2/rGO Composite as an Anode Material for High-Performance Potassium-Ion Battery.

Potassium-ion batteries (PIBs) have been widely studied owing to the abundant reserves, widespread distribution, and easy extraction of potassium (K) resources. Molybdenum disulfide (MoS2) has received a great deal of attention as a key anode material for PIBs owing to its two-dimensional diffusion channels for K+ ions. However, due to its poor electronic conductivity and the huge influence of embedded K+ ions (with a large ionic radius of 3.6 Å) on MoS2 layer, MoS2 anodes exhibit a poor rate performance and easily collapsed structure. To address these issues, the common strategies are enlarging the interlayer spacing to reduce the mechanical strain and increasing the electronic conductivity by adding conductive agents. However, simultaneous implementation of the above strategies by simple methods is currently still a challenge. Herein, MoS2 anodes on reduced graphene oxide (MoS2/rGO) composite were prepared using one-step hydrothermal methods. Owing to the presence of rGO in the synthesis process, MoS2 possesses a unique scaled structure with large layer spacing, and the intrinsic conductivity of MoS2 is proved. As a result, MoS2/rGO composite anodes exhibit a larger rate performance and better cycle stability than that of anodes based on pure MoS2, and the direct mixtures of MoS2 and graphene oxide (MoS2-GO). This work suggests that the composite material of MoS2/rGO has infinite possibilities as a high-quality anode material for PIBs.

Cu (II)-based metal-organic framework functionalized with graphene oxide as a sorbent for the dispersive micro-solid-phase extraction of losartan potassium from water

In this study, a new metal–organic framework (MOF) based on copper (II) functionalized with graphene oxide (MOF-Cu@GO) was successfully synthesized and applied as an efficient sorbent for dispersive micro-solid phase extraction (D-μSPE) of losartan potassium (LP) from water. The MOF-Cu@GO sorbent was characterized using DRX, FTIR, XPS, TGA, RAMAN, BET, SEM, EDX, and potential Z. The influence of different parameters in the D-μSPE method was studied and optimized using the fractional factorial design 25–1 and central composite design. The results indicated that the adsorption process was spontaneous and endothermic followed the pseudo-second order model kinetics and the Freundlich isotherm. The maximum adsorption capacity of MOF-Cu@GO sorbent was 415 mg g−1. The adsorption mechanism proposed of LP onto MOF-Cu@GO proceeded via electrostatic interaction, hydrogen bonds, unsaturated sites of the ligand, and π-π interactions. The microextraction procedure was followed by determination of LP with high performance liquid chromatography (HPLC–UV-Vis). Under optimized conditions, the limits of detection and quantitation were found to be 25 and 80 ng ml−1 respectively, the method exhibited a linear response (r = 0.998) in the concentration range of 0.1–50 µg ml−1 of LP, with a relative standard deviation less than 2% (n = 5). The D-μSPE method showed preconcentration factor of 684.9 and high percentage of LP extraction of 99.78% ± 2.62, the accuracy of the method was demonstrated by studying the recovery of LP from water samples of 100.3 ± 1.06. The material obtained can be used up to 3 cycles with time for the sorption and determination of 30 min indicating good stability and reusability. The MOF-Cu@GO proposed is an efficient and fast sorbent in the D-μSPE for determination of LP from aqueous solutions.

Extraction and separation of potassium, zinc and manganese issued from spent alkaline batteries by a three‐unit hydrometallurgical process

AbstractBackgroundBatteries play a vital role in meeting global energy needs. When their life cycle concludes, improperly discarded spent batteries can pose environmental risks primarily due to their metal content. In this sense, the recycling of metals contained in spent batteries could mean a huge advantage if they are extracted and purified using environmentally friendly processes.ResultsIn this study, the recovery of potassium (K), zinc (Zn) and manganese (Mn) from alkaline batteries was performed using a hydrometallurgical process consisting of neutral, acid and acid reductive leaching steps at room temperature and atmospheric pressure to extract K, Zn and Mn. In the neutral leaching step, 76.8 ± 3.4 (wt. %) of the K present in the spent batteries was extracted. Thus, in the acid leaching step, 90.9 ± 0.1 (wt. %) of the initial Zn and 36.7 ± 0.4 (wt. %) of the initial Mn was extracted using sulfuric acid (H2SO4) 2 M. In a subsequent acid reductive leaching step using H2SO4 2 M and oxygen peroxide (H2O2) 0.8 M as reducing agent, 8.7 ± 0.1 (wt. %) of the initial Zn and up to 49.4 ± 0.2 (wt. %) of the initial Mn were extracted.ConclusionThe three‐unit process led to an overall extraction of 99.6 ± 0.3 (wt. %) of Zn and 86.1 ± 0.1 (wt. %) of Mn. Regarding the latter step, the extraction was not 100% because Mn complexes which are nearly insoluble were generated. This shows that extraction of valuable minerals from industrial residues is possible by hydrometallurgical processes.This article is protected by copyright. All rights reserved.

Selective extraction of potassium from raw nepheline materials

The global aluminium industry is ever-changing and primarily relies on bauxite as its traditional source. However, due to the finite reserves of processed bauxite, alternative sources need to be found. Nephelines have emerged as potential alumina sources. In addition to alumina, nepheline processing can yield marketable products such as soda, potash, cement, and rare metals.The objective of this study was to identify the ideal conditions for selectively extracting potassium from alkaline leaching solutions while separating it from sodium alkali, aluminium, and silicon during the comprehensive processing of nepheline syenites from the Kubasadyr deposit. This approach involved a two-stage hydrothermal leaching process with an incremental calcium addition. Under optimal conditions, the potassium extraction in the alkaline solution reached 93.91 %. The resulting leaching solution served as a feedstock for potassium sulfate production through the crystallization method. The preliminary selective separation of potassium played a crucial role in mitigating its adverse effects on the extraction of aluminium, which is the primary processed product; thus, the economic viability of production was enhanced.

Recovery of Potassium from Pyrolysis Product of Sugar Fabrication Waste Carbonation Cake and Vinasse Mixture and Production of Adsorbent for Wastewater Treatment

In this study, percolation tests with water were carried out on the products that were subjected to pyrolysis and obtained in order to carbonize the organics in the vinasse carbonation cake mixtures. For this purpose, the mixtures prepared from the concentrated vinasse supplied from Sugar Factory and the carbonation cake supplied from Sugar Factory were heated at 500 °C for 4 h, and the extractability and dissolution rate of potassium into water were determined by leaking water over the products. The ability of the residue to remove methylene blue from the aquatic environment was determined. It should be emphasized that the solid residue from the potassium extraction has a considerable amount (289–370 mg/g) and a basic dye removal capacity greater than that of the raw carbonation cake (208 mg/g). COD value in the extract of the pyrolysis product with a cake/vinasse ratio of 0.5 was determined as 970 mg/l with a significant increase. The methylene blue removal capacity of the extraction residue samples obtained in this group of experiments decreases as the dry cake–vinasse ratio increases. It should be emphasized that the composite product obtained by taking advantage of these results can be actively used in the production of compound fertilizer.

Review on K-Feldspar Mineral Processing for Extracting Metallic Potassium as a Fertilizer Resource

The K-feldspar mineral is an insoluble potassium resource with a high potassium content and the most extensive and abundant reserves. To address the insufficient supply of soluble potassium fertilizers in China, the application of appropriate processing methods to extract potassium from K-feldspar and transform it into a soluble potassium fertilizer is of great significance. To date, various techniques have been developed to extract potassium from K-feldspar and produce a soluble potassium fertilizer. This review summarizes the main methods, i.e., the hydrothermal, high-temperature pyrolysis, microbial decomposition, and low-temperature methods, for potassium extraction from K-feldspar. The mechanisms, efficiencies, impact parameters, and research progress of each potassium extraction method are comprehensively discussed. This study also compares the merits and drawbacks of the individual methods in terms of potassium extraction efficiency and practical operating conditions. The species of additives, reaction temperature, reaction time, particle size of K-feldspar, and dosage of additives significantly affected the potassium extraction efficiency. Moreover, the combination of different methods was very effective in improving the potassium extraction efficiency. This review elaborates the research prospects and potential strategies for the efficient utilization of the K-feldspar mineral as a fertilizer resource.

A novel potassium‐containing layered oxide for the cathode of sodium‐ion batteries

AbstractLayered oxides are successful cathode materials for sodium‐ion batteries. Many of these oxides show interesting kinetic behavior but have poor structural stability. To overcome this limitation, an alternative material containing potassium in the interlayer space in trigonal prismatic coordination is studied here. The transition‐metal layers are formed by sustainable transition elements such as iron and manganese. The solid was prepared using a sol–gel procedure that led to a product with relatively high purity, with a Pʹ3‐type structure indexable in the C2/m space group of the monoclinic system. Its electrochemical behavior was studied in sodium metal half‐cells. When the cell is charged up to 4.3 V, it is observed that the potassium extraction is not complete. The subsequent discharge of the cell is associated with the intercalation of sodium from the electrolyte. Thus, it is possible to incorporate a greater number of alkaline ions than those extracted in the previous charge. The residual potassium in the structure was found to be favorable to maintaining the structural integrity of the compound upon cycling. This can be explained by the beneficial effect of potassium, which would act as a structural “pillar” in the interlayer, which would reduce structural degradation during cycling.

Potassium Vanadium Fluorides as Positive Electrode Materials for K-Ion Batteries

Potassium-ion batteries (KIBs) have attracted much attention as a potential high-voltage and high-power secondary batteries due to a low standard electrode potential of K+/K in carbonate ester-based electrolytes and weak Lewis acidity of K+ (1). We reported the K+ ion extraction/insertion reactions in polyanionic compounds at a high average working potential of > 4 V vs. K+/K, which should be attributed to the inductive effect of anion(2)(3). However, the specific capacity of polyanionic compounds is often limited by the high mass of the redox-inactive polyanion framework. In this study, we focused on potassium-containing vanadium fluorides, which have high theoretical capacity.We first created a triangle phase diagram of K-V-F systems considering with their theoretical capacities, as shown in Fig. 1a. Based on the theoretical capacity and valence of V, K3VF6 was selected and synthesized, and its electrode behavior and structural changes associated with potassium extraction were investigated as a positive electrode material for KIBs.K3VF6 was synthesized through a mechanochemical method after mixing stoichiometric ratios of KF and VF3 with 10 wt% Ketjen black (KB) and calcined to enhance crystallinity. The calcination was performed in an argon atmosphere at 300 °C. The working electrodes were prepared by mixing the synthesized sample with conductive carbon (KB) and binder (PVdF) at a weight ratio of 8 : 1 : 1 and applying it to an Al foil. The charge-discharge tests were conducted using coin cells with the prepared positive electrode, K metal counter electrode, and 1.0 mol dm-3 KPF6/EC : PC = 1 : 1 (v/v) or 5.6 mol kg-1 KFSA/G3 electrolyte (4).The Rietveld refinement of the synchrotron XRD pattern of K3VF6 is shown in Figure 1b. All of the diffraction peaks, except for VO peaks, could be indexed to the tetragonal space group I4/m. The refinement showed good fitting with a low R wp value of 6.18 %. The diffusion barrier of K+ ions in K3VF6 was calculated to 0.77 and 0.89 eV along b-axis and c-axis, respectively, by the BVEL method.Figure 1c shows the initial charge/discharge curve of K3VF6 electrode. The electrode exhibited a plateau at about 3.7 V and an initial discharge capacity of about 95 mAh g-1, which corresponds to a one-electron reaction of V4+/3+ (Figure 1c).Figure 1d shows ex-situ XAFS measurements to investigate the variation of V valence state during charge/discharge. After being charged to 4.3 V, the white line peak shifted to the higher energy and the pre-edge peak became stronger than the pristine spectra, indicating oxidation of V from trivalent to tetravalent during charge. The white line and the pre-edge peaks of K3VF6 discharged to 2.0 V are almost identical to that of the pristine, showing reversible V3+/4+ redox. We will further discuss the structural changes during the K+ ion extraction/insertion process and the redox behavior of V in the presentation.

K x Mn[Mn(CN)6] as a High Capacity Positive Electrode Material for Potassium Batteries

Recently, Na-ion and K-ion batteries have attracted attention as next-generation secondary batteries.1 Prussian blue analogues (PBAs) are promising cathode materials for these batteries. In 2014, it was reported that Na x Mn[Mn(CN)6] exhibited higher capacity in Na cells than the theoretical capacity based on Mn2+/3+ redox, which could be attributed to the reduction of Mn in [Mn(CN)6] to monovalence.2 Thus, PBA with Mn at the C-coordination site exhibits unique properties, but there is no report of high capacity in K cells. In this study, K x Mn[Mn(CN)6] (KMnHCM) was synthesized, and K+ ion extraction/insertion properties were evaluated. KMnHCM was synthesized by the solution precipitation method.3 The solution was sufficiently deoxygenated by bubbling nitrogen gas, and synthesis was performed under N2 atmosphere. The obtained samples were washed three times with deionized water under N2 atmosphere, and then dried at 150 °C under vacuum. The active material was mixed with conductive carbon (KB) and binder (PVdF) at a weight ratio of 7:2:1 in a glove box under an Ar atmosphere. Galvanostatic charge-discharge tests were conducted in a two-compartment three-electrode cell using a composite electrode coated on an Al foil as the working electrode, an activated carbon counter electrode, and an Ag+/Ag reference electrode. Figure 1(a) shows the X-ray diffraction (SXRD) patterns and Rietveld refinement results of the synthesized sample. The diffraction patterns of KMnHCM can be attributed to the monoclinic structure with space group P21/n and are almost identical to that previously reported. SXRD patterns were successfully fitted with the satisfied R values, and the composition of KMnHCM was estimated to be K1.87Mn[Mn(CN)6]0.96·0.29H2O. Figure 1(b) shows the charge-discharge curves of KMnHCM. The electrode showed an initial charge capacity of 163 mAh g-1 and an initial discharge capacity of 220 mAh g-1, corresponding to respective ~2.0 and 2.76 potassium extraction and insertion, respectively, from/into K x Mn[Mn(CN)6]. The discharge capacity exceeds the theoretical capacity of 160 mAh g-1 based on the Mn2+/3+ redox of K1.87Mn[Mn(CN)6]0.96·0.29H2O. Furthermore, the additional plateau was observed at the low voltage of around 1.5 and 1.7 V in the discharge and charge curves, respectively. The extremely high capacity and the third plateau at low voltage are similar to Na x Mn[Mn(CN)6] in Na cells.2 Thus, the third plateau would be attributed to the reversible redox of [MnII(CN)6]4-⇄[MnI(CN)6]5-. In the talk, we will further discuss the charge-discharge mechanisms, including redox behavior and structural changes of KMnHCM during charge/discharge.

Nitric Acid and Organic Acid Mixture Show Less Deviation in Extractability of Potassium Between Field-Moist and Air-Dried Soil

ABSTRACT Air-drying of soils for testing can cause fixation/release of potassium (K), showing a K status different from that of the field. We compared different extractants to find one with the least deviation in K-extractability between field-moist and air-dried soils. We chose two treatments (No-K and 150% of recommended K fertilization) of a field experiment (maize-wheat) for the study. Field-moist soil (0–15 cm) was collected at 3, 4, 5, 6, 7, 8, 23, 24, 25, and 26 days after the irrigation (DAI) from each replicated plot at the flowering stage of the 2018–19 wheat crop. Soil K, before and after air-drying, was extracted with 1 M ammonium acetate (NH4OAc), 0.1 M nitric acid (HNO3), 0.01 M calcium chloride (CaCl2), and 0.01 M organic acid mixture (OAM, mixture of 0.0025 M each of citric acid, malic acid, tartaric acid, and oxalic acid). Air-drying significantly (P < .05) affected the soil K for all methods except HNO3 in plots without K fertilization. However, air-drying’s effect on K release was more pronounced in No-K soils with high initial moisture content (>10%). Averaged over K-fertilization and initial soil moisture, the K-extractability using HNO3 and OAM showed the least deviation (9.6% for both) by air-drying. It was significantly (P < .05) lower than NH4OAc or CaCl2, which showed as high as 21.1–23.0% deviation due to air-drying. Hence, one should use 0.1 M HNO3 or 0.01 M OAM instead of 1 M NH4OAc to get an available K status closer to that in the field.

Effect of thermal pretreatment on the two-stage extraction of aluminum, sulfur and potassium from a fine-quartz bearing alunite

The extraction of aluminum, sulfur, and potassium from an alunite ore (Ghazvin, Iran) was studied by roasting followed by two-stage alkaline leaching. In the roasting stage, the effects of several key parameters including temperature (520 to 620 °C), reaction time (30–150 min), particle size (0.075 to 10 mm), and furnace medium (with and without diesel fuel and with charcoal) were investigated on the leachability of sulfur and potassium by sodium carbonate and of aluminum by sodium hydroxide. The first leaching stage was carried out with sodium carbonate at a pulp density of 20% (w/w), a reaction time of 4 h, a particle size of less than 75 µm, a temperature of 95 °C and a ratio of sodium carbonate to alunite of 1.5:1. The highest extractions of sulfur and potassium (99.9 % for both elements) were obtained with the ore roasted at 620 °C, a particle size of 3 mm, and a roasting time of 90 min. The extractions were significantly increased by increasing the temperature and roasting time. The second stage of leaching was conducted at the temperature of 95 °C, leaching time of 6 h and the sodium hydroxide concentration of 5 M at 15 % pulp density. The highest aluminum extraction (95.3 %) was obtained by reductive roasting with charcoal at a temperature of 570 °C, a roasting time of 30 min, and a particle size of less than 3 mm. For potassium and sulfur extraction, increasing the roasting temperature, reaction time and diesel fuel addition (above 3%) resulted in a decrease in aluminum extraction, which was attributed to the conversion of the alumina phase to a stable phase. The results of this study show that alunite ore could be an interesting alternative for alumina production.

Extraction of Li, K, and Rb from zinnwaldite by chlorination roasting with CaCl2

The extraction of lithium, potassium, and rubidium from lithium mica zinnwaldite was investigated using high-temperature roasting with solid calcium chloride, followed by water leaching of the resulting sinters. This study examined the impact of roasting temperature, heating rate, roasting time, and the calcium chloride content within the roasting mixture on the extraction efficiency of alkali metals. Based on the observed phenomena, a comprehensive reaction mechanism for alkali metals chlorination was proposed.The crucial factors of the roasting process are the roasting temperature and the calcium chloride content within the roasting mixture. The optimal results were achieved when a mixture containing four times the stoichiometric amount of calcium chloride was roasted at 1000 °C for 20 min with a heating rate of 10 °C/min. Under these conditions, 77 % of lithium, 90 % of potassium, and 90 % of rubidium were successfully extracted.The proposed chlorination mechanism of zinnwaldite roasting involves three successive stages:a)Chlorination of alkali metals between 500 and 650 °C primarily via the surface reaction of calcium chloride with zinnwaldite before the mineral decomposition initiates.b)Decomposition of zinnwaldite between 650 and 850 °C, with a preferential chlorination of potassium and rubidium due to their better accessibility for the chlorinating agent after the structural disruption of the original mineral.c)Chlorination of lithium as a result of the reaction between calcium chloride andβ-spodumene, a decomposition product of zinnwaldite.During the roasting process, the emission of fluorinated gaseous compounds was observed, along with the reaction of chlorine with iron. This reaction consumes the chlorinating agent and eventually leads to the generation of chlorine gas as a result of the decomposition of chlorinated iron compounds.

The Leaching Behavior of Potassium Extraction from Polyhalite Ore in Water.

The extraction of potassium from polyhalite ore (K2SO4·MgSO4·2CaSO4·2H2O) can help alleviate potassium resource shortages in China. In this study, the leaching behavior of potassium extracted from polyhalite ore in water was investigated using leaching experiments and kinetic analysis. The effects of various factors, such as liquid-to-solid ratio, leaching temperature, leaching time, and polyhalite ore particle size were comprehensively studied. It was found that high temperatures improved the reaction rate and efficiency at the beginning (1-15 min) but reduced the final leaching efficiency of potassium. And this phenomenon is discussed from the aspects of the dissolution-reprecipitation of potassium, newly formed solid products during the leaching process, and leaching thermodynamics. The leaching of potassium followed the Avrami model, with an apparent activation energy of 26.29 kJ/mol. Additionally, it was determined that the mixed controlled step (surface chemical reaction and diffusion) was the controlling step during potassium leaching. This study clarified the leaching mechanism of the polyhalite in water, and the causes of hindering the leaching of potassium were analyzed. The research results can provide theoretical reference and solutions for parameter design for the enhanced leaching process and selection of leaching agents in the future.

Residue after the extraction of potassium and chlorine from by-pass dust as a new raw material for the synthesis of low-emission Portland clinker

By-pass dusts are waste products formed during the production of Portland clinker. Due to the high amounts of chlorine in by-pass dust, they cannot be reused in cement production. Mineral fertilizer producers have the technology to recover potassium from by-pass dust, during which unwanted chlorine is simultaneously extracted. Due to the high content of non-carbonated CaO in the residue after extracting potassium and chlorine from by-pass dust, this material can be a very valuable ingredient in the production of Portland clinker. This paper aims to present the possibility of producing low-emission Portland clinker using the residue after extracting potassium and chlorine from by-pass dust. Using the maximum amount of extraction residue in the raw material sets from which Portland clinker is produced reduced emissions by 407.6 kg CO2 per Mg of Portland clinker, compared to Portland clinker produced from natural carbonate raw materials. Additionally, cements made from clinkers calcined with extraction residue showed better strength increases after 2, 7, 28, and 90 days of curing compared to reference cement made from Portland clinker calcined with natural carbonate raw materials.