Potash Brine Research Articles

Recyclable Adsorbents for Potash Brine Desalination Based on Silicate Powder: Application, Regeneration and Utilization

Silicate mineral powders (SMP) from weathered granite soil from Kazakhstan are proposed for the desalination of potash brines containing sodium, potassium and chloride ions. Batch adsorption experiments using acid-treated silicate (AS) achieved a Na+/K+/Cl− recovery of ~13/28/6 mg/g. An isothermal study best fitted the Freundlich and Dubinin–Radushkevich models for Na+ and K+/Cl−. The kinetic data were best modeled by pseudo-second-order kinetics for Na+/K+ and pseudo-first-order for Cl−. Thermodynamic calculations showed spontaneity under natural conditions. For Na+/K+, physisorption is accompanied by ion exchange. To study the possibility of sorbent reuse, several cycles of K+/Na+ adsorption–desorption were carried out under optimal conditions. AS selectively adsorbed potassium ions, maintaining a high effectiveness during five cycles providing K-form silicate fertilizers. Leachates of spent AS contain high concentrations of K/Na/Ca/Mg and other microelements essential for plants. Thus, SMP resolve two issues: the desalination of brine and the provision of fertilizer.

Halogenases of Qarhan Salt Lake in the Qaidam Basin: Evidence From Halite Fluid Inclusions

The fluid inclusion composition of halite can help track chemical composition of ancient fluids and, thus, serves as a reliable index to analyze ancient brine in salt lakes. Qarhan Salt Lake (QSL) is the largest potash brine deposit in China. Although the mixing of modern river water and Ca-Cl deep water is widely accepted as potassium formation, the mixing characteristics in the time domain and driving factors of deep water are still unclear. Here, the chemical composition of fluid inclusions in primary halite samples collected from the ISL1A borehole in QSL was measured by LA-ICP-MS technology. The analysis results show that, during the formation stage of the S4 salt layer in QSL, the main potassium salt layer, the contents of Ca2+ and Sr2+ in brine increased significantly. There is evidence confirming that Ca-Cl deep water is beneficial to the enrichment of potassium and the surrounding rivers generally develop terraces. It suggests that, during the formation stage of the QSL potassium salt layer, more Ca-Cl inflow water of the northern margin supplies the salt lake, inferring that it was driven by tectonic activities. In addition, the chemical composition of halite fluid inclusions shows that there is an anomaly in geochemistry at the early stage of salt formation in QSL. By combining the time of tectonic activities, it is inferred that the anomaly is not caused by tectonic activities but maybe caused by a salt-forming event. This work indicates that deep water and tectonic movement have a huge impact on the evolution of salt lakes. Therefore, it is necessary to consider the influence of deep water and tectonic activities on the salt-forming evolution stage of salt lakes when studying the salt-forming evolution stage of salt lakes and paleoclimate by using salt lake deposition.

Internal cathodic protection to study the erosion‐corrosion of AISI 1018 carbon steel

AbstractSteel elbows used in pipelines carrying potash slurry may undergo material loss due to mechanical erosion and/or electrochemical corrosion. Cathodic protection was used to study the effects of flow velocity and slurry concentration on the protection current density required to maintain AISI 1018 carbon steel elbows at a set electric potential. A flow loop with a peristaltic pump was used to pump a slurry consisting of silica sand in a saturated potash brine through the steel elbows. The protection current density measurements were performed under varying slurry flow velocities of 2.5, 3.0, 3.5, and 4.0 m/s and varying slurry concentrations ranging from 0‐35 wt%. The results show maximum values of protection current density were required for mid‐range slurry concentrations. It is concluded that, within the parameters of study, high flow velocities require higher protection current density than low flow velocities. Furthermore, high flow velocities result in a local maximum protection current density being reached at lower slurry concentrations; conversely, a local maximum protection current density is reached at higher slurry concentrations in lower flow velocities. The contrast in local maximum protection current densities likely occurs due to additional particle‐particle collisions at higher velocities causing the maximum mass transfer rate of oxygen to be reached at lower slurry concentrations. SEM micrographs show that wear becomes more evenly distributed with increasing flow velocity due to the homogeneous distribution of particles in the flowing medium.

Synergistic Erosion-Corrosion Behavior of AISI 2205 Duplex Stainless Steel Elbows in Potash Brine-Sand Slurry and the Associated Microstructural Changes

Slurry erosion-corrosion damage to materials used in mineral processing industries occurs due to the combined effects of electrochemical and mechanical processes. In this study, AISI 2205 duplex stainless steel elbows were tested in a flow loop using slurries consisting 10, 20, 30, 40 and 50 wt.% sand particles and saturated potash brine. Erosion-corrosion tests were conducted at flow velocities of 2.5 and 4.0 m/s. The results of the gravimetric analysis revealed that erosion-corrosion rates increased with increasing particle concentration at both velocities. The elbows exhibited negative synergy for all operating conditions, which is attributed to the presence of passive oxide film on the surface. Microstructural examination of the eroded surfaces showed that materials removal occurred by cutting and plastic deformation. Electron backscattered diffraction analysis suggests that plastic deformation, which occurred approximately 4 µm below the eroded surface, led to the transformation of metastable austenite phase to martensite.

Non-Destructive X-Ray Microprobe Characterization of Corrosion at the Polymer/Steel Interface

This work used the unique capability of synchrotron x-rays to probe a buried polymer/metal interface with high energy resolution and spatial resolution on the micron scale. X-rays of sufficient energy can penetrate the organic polymer coating and interrogate heavier elements found at the interface. X-ray fluorescence (XRF) spectra can be collected provided the element specific energy of the fluoresced photon is sufficient to penetrate through the polymer coating. We characterized the interface beneath several polymer coatings on steel reinforcing bar after exposure to alkaline potash brine using the Soft X-ray Microcharacterization Beamline (SXRMB) at the Canadian Light Source. Characterization included correlated XRF maps for Fe, Mn, K and Cl as well as micro x-ray absorption near edge spectroscopy (µ-XANES) to analyze Fe corrosion products at certain areas of interest. By collecting Fe XRF maps with an incident beam energy of 7115 eV, we exploited the differences in absorption cross section between Fe metal and oxidized Fe species at this energy. The result is a map with excellent contrast between corroded and non-corroded regions of the interface. This provides a relatively quick means to locate localized anodic zones beneath opaque polymer coatings without a visual indicator (i.e. a blistered region of polymer). XRF maps for K and Cl showed these elements were segregated at the interface with K hotspots providing a surrogate measurement for cathodic activity at the interface. µ-XANES analysis showed evidence of Fe corrosion products that varied somewhat from those reported in previous studies, owing to our efforts to perform sample handling in an inert atmosphere after the exposure to potash brine. The speciation of Fe combined with the spatial distribution of Mn, K, Cl provided evidence to support previous literature models pertaining to mechanisms of coating delamination and the spread of corrosion at the polymer/metal interface.

Erosion-corrosion of 90° AISI 1018 steel elbows in potash slurry: Effect of particle concentration on surface roughness

A five-day erosion-corrosion study was conducted to investigate the effect of particle concentration on surface roughness of AISI 1018 steel elbows. Tests were performed in a flow loop containing 10, 20 or 30 wt.% particle concentration and saturated potash brine at a slurry flow velocity of 4 m/s. Optical profilometry analysis showed that surface roughness was higher at the entry region of the elbows than those of the middle and exit regions. Scanning electron microscope images of the worn surfaces revealed the presence of gullies and islands on the entry regions at low particle concentration, but ridges and valleys were formed on the middle and exit regions at higher particle concentrations. In general, results showed that surface roughness, mass loss and hardness at the exit regions increased with increasing particle concentration.

Evaluating Brine Deposits Using Borehole Magnetic Resonance

Brine mining is an important source of elements such as potassium, iodine, lithium, and bromine that occur in solution in groundwater, typically in shallow brines occurring beneath saline or dry lakes or in deep brines in sedimentary basins. Where feasible, brine mining is an attractive alternative to conventional mining due to lower surface and environmental impact and lower OPEX than conventional mining operations. As with any resource, evaluating brine deposits requires developing an understanding of how much resource is present and how it can be most economically produced. How much resource is present is a function of the bulk aquifer volume, the specific yield, and the brine composition, while the primary subsurface control on economic production is hydraulic conductivity, which dictates the rate at which the brine can be produced to surface. Specific yield and hydraulic conductivity are analogous to the free fluid volume and permeability quantities that are of interest in oil and gas resource assessment. Borehole magnetic resonance has been applied in the oil and gas industry for the evaluation of bound and free fluid volumes and permeability for over twenty years. These same methodologies are equally applicable in the evaluation of brine deposits, however the hypersaline brines that are targets for commercial development cause highly conductive borehole environments that can be extremely challenging for magnetic resonance measurements. Nevertheless, use of borehole magnetic resonance measurements to help evaluate a sulphate of potash brine deposit currently under assessment shows that such measurements can be employed successfully in these environments.

Sr isotope and major ion compositional evidence for formation of Qarhan Salt Lake, western China

Qarhan Salt Lake (QSL) is the largest potash brine deposit in the continental Qaidam Basin (QB) of western China. The origins of the Qarhan brines, whether from migration of Qaidam mega-paleolakes, paleoriver capture, or mixing of modern river water and Ca-Cl spring water, are controversial. Details about the origin (hydrothermal, diagenetic or both) of the Ca-Cl inflow waters entering QSL in the QB are unclear. Here we show from the strontium (Sr) isotope ratios of river waters, intercrystalline brines, spring waters, halite, gypsum, and Corbicula shells from Qarhan playa, that 87Sr/86Sr increases from Bieletan (western QSL) to Huobuxun (eastern QSL). This trend verifies that river water-spring water mixing has been operating at QSL for the past 50,000 years. Contributions of Ca-Cl inflow waters to the QB have profoundly influenced the brine evolution and mineralogy of salt deposits. Mixing between low Sr2+ concentration, low 87Sr/86Sr value of river waters and high Sr2+ concentration, high 87Sr/86Sr value of Ca-Cl spring inflow waters has produced various intercrystalline brines and salt deposits at QSL. Ca-Cl inflow waters and brines are enriched in Sr2+ and Ca2+ and depleted in Mg2+ and SO42−. These characteristics suggest brine-sedimentary rock (silicate) interactions at burial diagenetic or hydrothermal conditions. Ca-Cl inflow waters and brines have a similar Sr isotopic range as oilfield brines and celestite deposits in the QB, which also suggests a diagenetic-hydrothermal origin. Ca-Cl brines discharge as springs or seeps along fault zones in the QB. They are interpreted to reach the surface of the northern margin of Qarhan playa by topographically driven circulation.

X-ray microprobe characterization of corrosion at the buried polymer-steel interface

The simultaneous collection of x-ray fluorescence (XRF) intensity maps for several elements was combined with x-ray absorption near-edge spectroscopy (XANES) to perform a non-destructive study of polymer-steel interfaces exposed to high pH potash brine. Analysis of iron, manganese, potassium and chlorine XRF maps allowed the identification of anodic pits, disbonded areas containing precipitated corrosion products and several cathodic regions. Iron XANES was used to determine the phases of Fe corrosion products present. Our results confirm previous models of corrosion under polymer films where osmotic blisters are causally related to the spread of corrosion at the polymer-metal interface.

Slurry erosion-corrosion of 90° AISI 1018 steel elbow in saturated potash brine containing abrasive silica particles

Erosion-corrosion is frequently encountered in pipelines used in potash processing equipment and it may be a severe problem, causing rapid material degradation if the slurry flow velocity and solid concentration are high. In this study, the interaction between erosion and corrosion of 1018 steel 90° elbows (2.54 cm schedule 40 - long radius) was investigated in a continuous flow loop. Experiments were conducted using a slurry consisting of saturated potash brine and silica sand. The effects of solid concentration and flow velocity on erosion-corrosion damage of the steel elbow were investigated. The results indicated that increasing flow velocity and solid concentration increased the mechanical effects of particles on the tested elbows and hence increased the erosion-corrosion rates of the elbows. It was observed that there was a 56% synergy between erosion and corrosion at 2.5 m/s, but the synergy level decreased to 11% at 4.0 m/s.

Synergistic desalination of potash brine-impacted groundwater using a dual adsorbent

The impact of saline mining effluent has been a significant environmental concern. Natural and modified clay-mineral adsorbents have been receiving increasing attention for salinity reduction of brine-impacted water, especially for natural resource extraction sites and surrounding environments. In this study, a dual-adsorbent treatment based on the sequential application of calcined layered double hydroxide (CLDH) and acid-treated zeolite was developed, evaluated and characterized for the desalination of potash brine-impacted groundwater. Potash brine produced by conventional potash mining in Saskatchewan (Canada) contains a large amount of Na+, K+ and Cl−. The CLDH and acid-treated clinoptilolite zeolites were combined to sequentially remove Cl− and Na+. A series of batch adsorption experiments were conducted for synthetic saline water and potash brine-spiked groundwater using various combinations of adsorbents: natural zeolites (NZ) or acid-treated zeolites (AZ) with or without the CLDH pretreatment. The experiment revealed that the Na+ removal percentage was synergistically increased by the dechlorination pretreatment using CLDH, and further improved by AZ. The CLDH-AZ dual adsorbent achieved a Langmuir Na+ adsorption capacity of 24.4mg/g, a significant improvement over conventional approaches to zeolite-based desalination. Using the brine-impacted groundwater with a high sodium adsorption ratio (SAR) of 13.3±0.1, the CLDH-AZ dual adsorbent decreased the concentrations of Na+, K+, and Cl− by 87, 97, and 87%, respectively (below drinking water standards). It also exhibited the additional advantages of neutralizing the effluent pH and decreasing the hardness, SAR, and total dissolved sulfur concentration. This study addresses the removal mechanisms, which are associated with the structural memory effect, dealumination, protonic exchanges, and zeolite porosity changes. Synchrotron-based scanning transmission X-ray microscopy analyses provided visual evidence of sodium adsorption sites (SiONa and AlONa) associated with dealumination in the acid-treated zeolites. This study is the first report that demonstrates the synergy of the CLDH-AZ dual adsorbent treatment for potash brine-impacted water.

Salts Removal from Synthetic Solution-Potash Brine by Non-Planted Constructed Wetlands

Four pilot-scale non-planted constructed wetlands (CWs) were employed to study the fate and transport of the two dominant chloride salts contained in brine resulting from solution mining activities in the potash industry. The simulated brine contained a 10:1 ratio of NaCl:KCl based on authentic brine characteristics. The multi-layer soils functioned as a main salt filtering component comprising of Regina Clay, sand and gravels. The CW systems were operated in three batches of 16 days (experiments 1–3). K+ ions were removed by 92% (4.6 mg/L) from the effluent, while Cl− and Na+ were removed in lower proportions of 51% (85.3 mg/L) and 45% (53.2 mg/L), respectively. Over time, the retained quantities of the three target salt ions decreased, indicating that clay sorption capacity may have been reached. This study demonstrated that Regina Clay has substantial sorbent capacity for salt ions contained in simulated potash brine solution.

The corrosion wear behaviour of selected stainless steels in potash brine

Tests were conducted at 25 and 85 °C to evaluate the corrosion wear resistance of selected stainless steels in potash brine using a reciprocating motion wear apparatus. Four materials were tested: Ferralium 255 (UNS S32550), AL6XN (UNS N08367), 254SMO (UNS S31254) and AISI 1018 (UNS G10180) for comparative purposes. The evaluation methods employed included weight loss analysis, optical microscopy and scanning electron microscopy (SEM). The results show that Ferralium 255 has superior corrosion wear resistance in potash brine environment compared to AISI 1018 plain-carbon steel and the other stainless steels tested. Wear surface analysis using SEM shows evidence of brittle fracture damage, which is attributed to the presence of Cl −.

Toxicological effects of potash brine on bay of Fundy marine organisms

The acute lethality and sublethal heavy metal contamination potential to marine organisms of a waste brine solution from a potash mining operation were determined. The brine was acutely lethal to marine organisms of the Bay of Fundy, Canada, at concentrations between ≅47 and 55‰ salinity (96-h LC 50 values: threespine stickleback, Gasterosteus aculeatus, 47·7‰; polychaete worm, Nephtys incisa, 52·5‰; blue mussel, Mytilus edulis, lethal to whole animal and reduced ciliary activity of gills above 55‰). The brine diluted to sublethal concentrations (≤40‰) contained manganese (≤ 49·5 ×), copper and zinc (≤ 5·2 ×), lead (≤ 2·6 ×) and cadmium (≤ 0·7 ×) in decreasing order of enrichment relative to control seawater. Copper was accumulated in mussels exposed to these solutions over 44 days to the greatest degree (4 ·4 ×), followed by manganese and lead. Tissue lead concentration reached a steady value within 44 days and cadmium was not accumulated.

Potash guar gum--a source of halophilic bacteria.

Moderate and extreme halophilic microorganisms have been isolated from guar gum solutions dissolved in potash brine for use in sylvite froth flotation. Tentative identifications have been made of vibrio, Halobacterium, and Halococcus species. Reinoculation of these isolates into guar gum solutions has shown that they are not carbohydrate-utilizing strains, but instead metabolize the contaminating proteins present in guar.