Soluble Mineral Salts Research Articles

Experimental Study of Lithium Extraction in the Solid-Liquid Conversion of Low-Grade Solid Potash Ore

There are considerable reserves of low-grade solid potash resources in the shallow part of Mahai Salt Lake in the Qaidam Basin, and the lithium brine resources resulting from solid–liquid conversion and mining are quite abundant. The comprehensive utilization of these resources is an important and urgent problem. In this study, to fully utilize these resources, the shallow low-grade solid potash ore in Mahai Salt Lake was used for systematic simulated ore dissolution experiments, combined with geochemical and X-ray diffraction analyses. The following key results were obtained: (1) Most Li+ in the Mahai mining area was deposited on the soluble salt minerals in silt or clay, and the appropriate concentration of solvent can help to dissolve more Li+ and K+; (2) the saturation time of Li+ was longer than that of K+. Therefore, the dissolution time for the mine can be appropriately extended during the production process to dissolve more Li+; (3) the solid–liquid conversion aqueous solution mining method can separate the lithium part of clay deposits and is associated with salt rock in the brine, which is a potential lithium resource. These experimental results provide a theoretical basis for salt pan production.

LOW-TEMPERATURE GEYSERITE AND EPHEMERAL MINERALS OF THE MOGOYSKY THERMAL SPRING (NORTHERN TRANSBAIKALIA, BAIKAL RIFT ZONE)

During hydrogeochemical testing of the Mogoisky thermal spring in Northern Transbaikalia, 5 samples of modern mineral sediments were taken, in two of which opal is the main component of geyserite, and in the other three carbonates, fluorides and sodium sulfates predominated. Calculations of deep temperatures showed that the formation of geyserite is associated with low-temperature hydrotherms and is explained by a decrease in their temperatures during discharge. Deposits of easily soluble salt minerals occur on the evaporation barrier, during rainy periods they can completely dissolve and disappear.

Intensification of the flotation separation of potash ore using ultrasound treatment

The difficulties of beneficiation of the potash ores by flotation is controlled by the structural similarity of the soluble salt minerals such as halite NaCl and sylvite KCl leading to the same surface properties and reactivity of those minerals when cationic reagents are used as collector. In this work, the effect of sonication on the selective flotation and separation contrast between sylvite KCl and halite NaCl in saturated salt solutions was investigated. The flotation experiments were performed on the potash ore samples from the Verkhnekamskoye deposit, Russia, using primary amine as the collector. Different particle sizes (0.5–1 mm, 0.25–0.5 mm, and 0.1–0.25 mm) with similar contents of K (26–29 %) and Na (16.5–18 %) and the same mineralogical compositions were studied. Pulp sonication was performed during the conditioning and/or flotation stages at 30 % solid content in a mechanical flotation machine using an ultrasonic generator at powers from 10 to 75 W at a resonant frequency of 20 kHz. In the absence of the sonication, the maximum recovery of sylvite was obtained for the size fraction of 0.25–0.5 mm (93.99 %) while the sylvite recovery was low for the coarse-grained fraction (0.5–1 mm). The lowest flotation selectivity was observed for the fine-grained ore sample (0.1–0.25 mm). The combined ultrasonic treatment of this sample during conditioning and flotation approximately halved the recovery of NaCl in the potash concentrate (from 17.9 % to 9.9 %) and increased the KCl recovery from 89.9 % to 95.9 %. The addition of a frother increased significantly the sylvite recovery under sonication for coarse size fraction while the effect was less prononoced for the intermediate size fraction. The enhanced flotation selectivity between KCl and NaCl under sonication was attributed to the increased detachment of weak hydrophobic NaCl particles from air bubbles according to the particle size and mode of treatment. The collector desorption from the halite surface unrevealed by the diffuse reflectance infrared spectroscopy was suggested as a factor controlling the selective detachment of low hydrophobic particles under sonication. Therefore, based on our results, a balance must be established between the particle size, collector consumption, ultrasound treatment power, and sonication method (during conditioning with reagents or/and flotation) to optimize the separation between NaCl and KCl.

Evolution of redox activity of biochar during interaction with soil minerals: Effect on the electron donating and mediating capacities for Cr(VI) reduction

Biochar in soil is susceptible to natural aging along with soil minerals, which might alter its electrochemical properties and redox reactions with contaminants. In this study, soluble mineral salts (FeCl3, MnCl2, AlCl3, CaCl2) and clay mineral (kaolinite) were selected to investigate the impact of co-aging with soil minerals on the redox activity of peanut-shell biochar for Cr(VI) reduction. Natural aging for 3-month induced oxidation of biochar with the decrease of reducing moieties, i.e., ‒C‒OH from 26.8–43.7% to 18.4–24.1%. Co-aging with minerals except for Mn(II) further decreased the proportion of ‒C‒OH to 6.94–22.2% because of the interaction between mineral ions and biochar, resulting in the formation of mineral-biochar complex and new minerals, e.g. β-FeOOH. Due to its reductivity, Mn(II) presented the least decrease or even slight increase of ‒C‒OH while itself was oxidized to Mn(III) and Mn(IV). The decline of ‒C‒OH caused the decrease of Cr(VI) reduction rate constant from 2.18 to 2.47 × 10-2 h-1 for original biochars to 0.71–1.95 × 10−2 h−1 for aged ones, of which co-aging with Fe(III) showed the lowest reduction rate constant among all minerals. The electron mediating capacity of biochar also decreased after aging alone or co-aging with Al, Ca, and kaolinite, while co-aging with Fe(III) and Mn(II) facilitated the electron transfer process, increasing the rate constant by 219.3–1237% due to electron mediation through valence transformation of Fe(III)-Fe(II) and Mn(II)-Mn(III). Given the abundance of soil minerals, it was essential to consider this crucial factor for redox reactions when applying biochar for soil remediation.

Effects of Dissociation Water Retention on Pore Structure Disintegration in Hydrate Sediments

During the depressurization process, natural gas hydrates (NGHs) decompose and release methane gas and water. Field experience shows that only 1% of the dissociation water is recovered, hindering the continuous pressure decline and further NGHs decomposition. The retention effect of the dissociation water on the pore structure is still unclear in NGHs sediments. In this paper, the hydrate sediment samples were tested for porosity, permeability, pore structure and clay minerals content, etc. The ions concentration change of solution was continuously measured using a conductivity meter to evaluate the disintegration mechanism of sediments. The results show that the pore structure of sediments tend to disintegrate under the action of dissociation water, leading to an increase in the ions concentration of dissociation water. According to the ions concentration curve, the sediment disintegration is divided into two stages. The rapid disintegration stage is mainly related to clay minerals. The slow disintegration stage is mainly related to the dissolution of soluble salt minerals. The initial water content is the main factor affecting the disintegration of the sediment skeleton. Under the condition of low initial water content, the sediment skeleton disintegrates instantaneously in dissociation water. When the initial water content exceeds 30.6–37.9%, the pore structure of sediments tends to be stable in dissociation water. Studying the effect of dissociation water on the sediment pore structure is helpful to understand the mechanism of low water production and to optimize the exploitation regime of gas hydrate.

Glauconite: An Indigenous and Alternative Source of Potassium Fertilizer for Sustainable Agriculture

Potassium (K) is regarded as a key player in plant growth. It has a significant role in crop productivity as one of the major nutrients. Thus, the addition of K fertilizers has supreme importance in supplying K to the plant requirement. Present K demand is satisfying by highly soluble and concentrated mineral salts; when those salts suddenly introduced into environments, naturally established ecological diversity may become disrupted, ultimately soil fertility is deteriorated. Glauconite is a natural and abundant mineral rich in K which can be used as a K fertilizer source for benefiting the agriculture sector. India has the largest deposition of an indigenous glauconitic sandstone which could offer a cheap and locally derived source of slow-releasing K fertilizer. Usage of glauconite in farming replaces K fertilizers, viable in terms of economic and environmental perspectives, aids in the provision of additional nutrients along with K, nourishes soil health, and helps in achieving sustainability in agro-ecosystem.

The Effect of Soluble Mineral Salts in Ceramic Brick Masonry

This work discusses the effects of soluble mineral salts on ceramic brick masonry walls at Petrolina, Pernambuco, Brazil, located 780 km from the ocean. To understand this phenomenon, a mapping of the pathologies originating from the effects of soluble mineral salts in Petrolina was carried out and wells were implemented to monitor the underground water supply in five points considered to be where the most frequent occurrence of the phenomenon takes place. Samples of soil, groundwater, bricks affected by the phenomenon and the level of chloride in the atmosphere of these localities were collected and analysed in the laboratory in order to characterize their properties. The results obtained indicate that the building pathological manifestations present in ceramic block walls, located in the study areas, are strongly correlated with the high content of soluble salts observed in the soil and groundwater samples collected than by the amount of chloride content in the atmosphere soluble salt levels. Clay sands are a type of soil more prone to underground water runoff and, because of this feature, provide a more favourable environment for rising moisture that transports soluble mineral salts to the masonry walls accelerating their degradation process.

A computational tool for designing BWRO systems with spiral wound modules

Deficiencies in commercial programs for the design of RO systems motivate the development of new ones that allow a flexible design and more realistic operating conditions for this type of systems. This work presents a computational tool for designing BWRO systems with spiral-wound modules. This algorithm has advantages over commercial software supplied by membrane manufacturers (such as ROSA, IMSDesign or Q+ Projection Software), whose trial-and-error approach results in a waste of time for the designer. The proposed program has an additional boundary condition: to achieve the maximum flux recovery without scaling due to the precipitation of sparingly soluble mineral salts (e.g., silica (SiO2), calcium carbonate (CaCO3), calcium sulphate dihydrate (denoted simply as CaSO4), barium sulphate (BaSO4), strontium sulphate (SrSO4) and calcium fluoride (CaF2)). The designer's liberty to change the constrains established by membrane manufacturers provides the user with a desired safety margin and more flexibility. A range of 1 to 8 elements in each pressure vessel, 1 to 3 stages and the possibility of inter-stage pumping are taken into consideration. The results are displayed in a multi-filterable and sortable table. This allows the user to see all possible solutions and choose the most appropriate. The algorithm also has a predictive model of the performance of RO systems, providing an estimation of the performance of the selected RO system in the long term. The program has been validated using the experimental data of four full-scale BWRO desalination plants, proving that the proposed program is closer to actual data than the computational tool supplied by the manufacturer.

Microstructure of Selected Mortars Undergoing Long-term Influence of External Environment

A facial wall is defined as an element used outside or inside which should have an attractive look. It is built from attractive wall elements using standard way of execution and joints filled with mortar appropriate for this type of wall element. From the point of view of durability, the mortar is a wall element which not only binds bricks but also takes part in humidity transport. It is associated with mortar microstructure which in comparison to clinker is characterized with high percentage of pores causing capillary flow and wall drying abilities. Mortars belong to the group of chemically active materials for which both internal as external factors are essential. The reason for internal corrosion are mortar components (binder, sand, water, additions). External corrosion includes all cases where mortar is threatened with external factors (CO2 gas, acid rain, temperature changes exceeding zero point, solution of soluble mineral salts originating from surrounding elements). The factors mentioned essentially influence mortar microstructure changes. This process is distributed in time. This work concerns the analysis of changes in quantity and distribution of pores resulting from many years of functioning of mortar in facial wall threatened with external factors. The researches were performed on a field test station localized in area of the University of Science and Technology in Bydgoszcz (Poland). Three facial walls with different mortars were chosen: Portland cement based mortar CEM I, Portland cement based mortar CEM I with plasticizer and cement-lime mortar. During construction of walls, standard beams were formed from mortars in order to perform basic tests and microstructure tests after 28 days of hardening.

Flotation chemistry of soluble salt minerals: from ion hydration to colloid adsorption

In this paper, recent progress with respect to the flotation chemistry of soluble salt minerals is reviewed, and some of the more relevant issues including the hydration states of ions, the interfacial phenomena of salt surfaces and the flotation behavior of selected soluble salts are discussed. Due to the high solubility, the flotation of most soluble salts has to be carried out in their saturated brines. Anecdotal evidence has suggested that the hydration states of the ions have significant influence on the physicochemical properties of the solutions, the surface charge and wetting characteristics of the minerals, the collector adsorption states and, further, the flotation behavior of the soluble salts. In this regard, reviewing past research findings, efforts are made to establish a correlation between the ion hydration states with the flotation behavior of the soluble salts. Further, advances in understanding the significance of colloid adsorption involved in the soluble salt flotation process are addressed, and future research efforts to understand the soluble salt flotation chemistry are suggested.

Surface chemistry considerations in the flotation of rare-earth and other semisoluble salt minerals

Semisoluble salt minerals are characterized by their ionic bonding and are distinguished from soluble salt minerals by their limited solubility in water. One group of semisoluble salt minerals being considered is the alkaline earth salt minerals, including fluorite (CaF2), calcite (CaCO3) and apatite (Ca5F (PO4 center dot)(3)), as well as celestite (SrSO4) and barite (BaSO4). Another group of semisoluble salt minerals being considered is the rare-earth salts, which include bastnaesite ((Ce, La) CO3F), monazite (CePO4) and xenotime (YPO4). Surface chemistry features of these selected semisoluble salt minerals are discussed with respect to flotation separations. First, the surface chemistry features of alkaline earth semisoluble salt minerals are reviewed, and then the surface chemistry features of rare-earth semisoluble salt minerals are examined. The discussion includes electrokinetic behavior, wetting characteristics and collector adsorption. Minerals & Metallurgical Processing, 2013, Vol. 30, No. 1, pp. 24-37. An official publication of the Society for Mining, Metallurgy, and Exploration, Inc.

Halite clogging in a deep geothermal well – Geochemical and isotopic characterisation of salt origin

The sandstone formation of the Middle Buntsandstein (Lower Triassic) in the geothermal well Groß Buchholz Gt1, Hanover, Northern Germany, was hydraulically stimulated to generate a heat exchanger surface, using 20000m3 of fresh water. After six months of enclosure the recovered water was oversaturated with respect to halite at surface conditions. Due to cooling induced precipitation a salt plug formed between 655 and 1350m depth in the tubing. While the Na/Br and the Cl/Br ratio of the recovered water reflect the signature of a relic evaporative solution the recovered water contains tritium, indicating a significant proportion of fresh water. Leaching experiments of the reservoir rocks point towards presence of traces of soluble salt minerals in the formation. Therefore we assume that the salinity cannot be attributed solely to halite dissolution nor to the production of a pure formation brine. The recovered water is a result of a combination of both salt dissolution by injected fresh water and of mixing with a formation brine which has undergone water–rock interaction. The calculated fresh water proportion in the recovered water is around 40%. The presence of salt mineral traces in pores of a target formation is a potential threat for the operation of geothermal wells, as cooling-induced salt scaling jeopardizes their performance.

Identifying, Evaluating, and Implementing Antiscalants in RO Reuse Applications

AbstractThe Orange County Water District (OCWD) operates a 70-mgd RO system as part of the Groundwater Replenishment System (GWRS), an advanced wastewater purification facility. Each of 15 5-mgd RO units consists of a three-stage array, operating at 85 percent recovery. As part of the operating strategy, antiscalant and pH suppression are used to limit third-stage precipitation of sparingly soluble mineral salts. Identifying successful antiscalants is extremely challenging. A variety of antiscalants with varying chemistries and capabilities present opportunities for optimizing RO processes, pricing, dosage, and pH adjustment. Recognizing the potential savings in RO pretreatment chemical cost, OCWD began antiscalant pilot-scale trials in 2009. However, failure to identify an effective product led to the trial's cancellation. Concurrently, the GWRS RO facility began experiencing third-stage permeability loss in all 15 RO units because the antiscalant was ineffective. This article discusses fast-track testin...

Surface Properties and Flotation Characteristics of Boron Minerals

Flotation of soluble salt minerals such as potash, trona and borax exhibits similarities because all are conducted in their brine solutions. The most commercially important boron minerals in the world are borax (Na2B4O7.10H2O), colemanite (Ca2B6O11.5H2O), ulexite (NaCaB5O9.8H2O), and kernite (Na2B4O7.4H2O). Most of them contain low grades when mined and must be upgraded by mineral processing techniques to commercially acceptable quality for the production of basic chemicals, such as boric acid. Boron minerals exhibit a spectrum of solubilities depending upon the cations in the lattice structure. Accordingly, a classification of semi-soluble (colemanite and ulexite) and soluble (borax and kernite) boron minerals may be appropriate as each class of minerals behaves differently in flotation. While borax has to be concentrated from its saturated brine, colemanite and ulexite can be recovered by flotation as is the case for other semi-soluble salt minerals. A common problem encountered in both classes of boron minerals is the presence of sig- nificant amounts of clay type minerals which adversely affect flotation recoveries in the form of slime coating. Despite the successful application of flotation technology in the potash industry, flotation has not yet been well developed for boron recovery. This may be attributed to inherent difficulties such as high ionic strengths, high viscosity brines, interaction of cations at the solid/liquid interface, and particularly the presence of clay minerals acting as persistent slimes. In this paper, we have reviewed the flotation chemistry studies on the interaction of boron minerals with anionic (sodium dodecylsulfate) and cationic (dodecylamine hydrochloride) surfactants along with the electrokinetics properties of boron minerals.

Numerical study of concentration polarization in a rectangular reverse osmosis membrane channel: Permeate flux variation and hydrodynamic end effects

Concentration polarization in a rectangular reverse osmosis (RCRO) and a laboratory plate-and-frame RO (PAFRO) membrane channels were investigated using a finite-element numerical model consisting of the fully coupled governing equations for fluid dynamics and mass transfer. The model considers both the concentration dependence of model parameters and axial variation of permeate flux. In both the RCRO and PAFRO channel geometries the flux varies axially along the membrane commensurate with the coupled development of the concentration boundary layer. For the case of the RCRO channel, the effect of permeate flux was quantified via the computed feed-side mass transfer coefficient (commonly used in estimations of concentration polarization) in terms of a dimensionless correlation for the average Sherwood number, S h ¯ = A 1 ( 1 + A 2 R e A 3 S c A 4 ( H / L ) A 5 R e ¯ p ) [ R e S c ( H / L ) ] 1 / 3 , that reduces to the form of the classical Lévêque solution in the limit of vanishing permeate flux. Simulations of desalting in a PAFRO channel demonstrated the importance of accounting for local permeate flux variability and coupling of the hydrodynamics and mass transfer model equations in order to predict local concentration variations and in particular local maxima of concentration polarization, especially in regions of flow recirculation where scaling by sparingly water soluble mineral salts could be first triggered should their concentrations exceed saturation.

Soluble salt minerals from pigeon droppings as potential contributors to the decay of stone based Cultural Heritage

This paper describes the salt content and pH evolution in solutions produced by the water-soluble extraction of accumulated pigeon droppings. Results demonstrate that these accumulations contain 4 % of soluble salts. Therefore, they are a plausible source of salts commonly found on buildings. These salts comprise halite, sylvite, potassium calcium sulphate, aphthitalite, apatite group minerals, weddellite and gypsum. The interaction of solutions formed from pigeon droppings with porous limestone was also studied. A noticeable deterioration in limestone due to acid attack was observed, including surface etching of rock-forming minerals.

The Significance of Interfacial Water Structure in Soluble Salt Flotation Systems

Flotation of soluble salts with dodecyl amine hydrochloride (DAH) and sodium dodecyl sulfate (SDS) collectors has demonstrated that the interfacial water structure and hydration states of soluble salt surfaces together with the precipitation tendency of the corresponding collector salts are of considerable importance in explaining their flotation behavior. In particular, the high concentration of ions in these soluble salt brines and their hydration appear to modify the bulk and interfacial structure of water as revealed by contact angle measurements and this effect is shown to be an important feature in the flotation chemistry of soluble salt minerals including alkali halide and alkali oxyanion salts. Depending on characteristic chemical features (salt type), the salt can serve either as a structure maker, in which intermolecular hydrogen bonding between water molecules is facilitated, or as a structure breaker, in which intermolecular hydrogen bonding between water molecules is disrupted. For structure making salts the brine completely wets the salt surface and no contact angle can be measured. For structure breaking salts the brine does not completely wet the salt surface and a finite contact angle is measured. In this regard it has been found that soluble salt flotation either with the cationic DAH or anionic SDS collector is possible only if the salt is a structure breaker.

Measurement of Interaction Forces between Silica and α-Alumina by Atomic Force Microscopy

Interaction forces between a silica sphere and an α-alumina substrate at various pH values were measured by atomic force microscopy (AFM). As expected, at pH values of 10.8 and 10.2 when the surfaces are similarly charged, a repulsive force was observed. On the other hand, at pH values of 5.5, 6.4, and 8.6 when the surfaces are oppositely charged, attractive forces were observed. Experimental force vs separation distance curves were found to be in good agreement with theoretical predictions based on electrostatic and van der Waals interactions. Interestingly, when the force/radius values at a particular separation distance were plotted against pH, the transition from an attractive to a repulsive force occurred at pH 9.3, which is very close to the point of zero charge (pzc) of α-alumina as determined from electrophoresis experiments. These results suggest that AFM force measurements can be used to estimate the pzc of materials. This method may be of particular significance for soluble salt minerals where conventional electrophoretic measurements are not possible at high ionic strengths. Finally, results from transmittance studies further confirmed the interaction between silica and alpha alumina particles in suspensions at various pH values as would be expected based on the results from atomic force microscopy measurements.

Fundamental aspects of soluble salt flotation

The sign of the surface charge for alkali halides in their saturated brines has been established from nonequilibrium electrokinetic measurements. These surface charge results for alkali halides are generally as expected from simplified lattice ion hydration theory. Based on this electrokinetic information, it has been demonstrated that the flotation of alkali halide salts is due to the adsorption of oppositely charged collector colloids by heterocoagulation. For example, the classic flotation separation of KCl from NaCl with alkyl amines is thus explained. Now, the surface charge.collector colloid adsorption hypothesis has been extended to successfully explain the flotation behavior of certain alkali oxyanions including nitrates and sulfates as well as double salts including schoenite (K 2SO 4·MgSO 4·6H 2O) and kainite (KCl·MgSO 4·3H 2O). As was done previously for the alkali halides, the sign of the surface charge for these alkali oxyanion salts was established from nonequilibrium electrokinetic measurements by laser-doppler electrophoresis. These results together with the results from flotation/bubble attachment experiments indicate that the surface charge/collector colloid adsorption hypothesis accounts for the flotation response of many different soluble salt minerals when alkyl amines and carboxylates are used as collectors.

Enhanced evaporation of saline water in multipurpose solar desalination units

Experimental results are reported for the continuous evaporation of saline water under enhanced solar energy input. A multipurpose solar desalination unit (MPSDU) has been introduced and tested. A dynamic flow of saline water introduced to the multi-channel evaporator is heated up to 60°C. Soluble mineral salts are selectively separated along the channels in addition to distilled water. The salts include NaCl, MgCl 2 and others.