Dolomite Surface Research Articles

The interaction mechanism of a novel polymer depressant with apatite and dolomite surface and its implication on flotation: Experimental tests and DFT calculation

The efficient removal of dolomite from phosphate ores is vital for the subsequent production of phosphate fertilizer. This work investigated the interaction mechanism of poly(sodium styrene sulfonate) (PSS) on apatite and dolomite surface and its implication on flotation through Micro-flotation, adsorption capacity, Zeta potential, SEM-EDS and density functional theory simulation. Flotation results proved that PSS was able to depress dolomite efficiently in broad pH range (8–12). Contact angle, Zeta potential, adsorption capacity and SEM-EDS measurement confirmed that PSS was more prone to adsorb on dolomite rather than that on apatite, which hindered sodium oleate (NaOL) to adsorb on dolomite but almost didn’t influence NaOL to interact with apatite surface. DFT calculations confirmed that the 2p orbital of oxygen atoms within sulfonate groups hybridized with 4s orbital of calcium and 3s orbital of magnesium atoms on dolomite surface to form OCa, OCa and OMg covalent bond, while PSS weakly physisorbed on apatite via electrical interaction, due to the significant difference in steric hindrance and active atom density. PSS exhibited good selectivity and environmental compatibility as dolomite depressant in the beneficiation of phosphate ores for sustainable production of phosphate fertilizer.

Study on the Reverse Flotation Separation of Smithsonite from Dolomite Using the Saponified 2-(4,4-Dimethylpentan-2-yl)-5,7,7-trimethyloctanoic Acid as a Collector

Dolomite, a prominent calcium-bearing gangue mineral found in carbonate-type zinc oxide ores, poses a significant challenge for effective flotation separation alongside smithsonite due to their highly similar surface properties. The present study explores the potential of 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctanoic acid (2-DMPT) as a collector for the reverse flotation of smithsonite from dolomite. Micro-flotation experiments indicated that saponified 2-DMPT exhibited superior collecting ability and selectivity for dolomite over smithsonite under highly alkaline conditions. Specifically, the flotation recovery of dolomite reached 62%, whereas only 6% of smithsonite was recovered in the flotation foam products. Zeta potential and attenuated total reflectance–Fourier transform infrared (ATR-FTIR) analysis revealed that changes in pH values had minimal influence on the collector’s adsorption onto dolomite, while significantly hindering its adsorption on the smithsonite surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis showed that 2-DMPT could form hydrophobic complexes with the active Ca2+ sites on the dolomite surface at pH 11.5. However, the interaction between smithsonite and carboxylic groups of 2-DMPT under the same conditions was relatively weaker, facilitating their reverse flotation separation. As a result, 2-DMPT shows promise as a potential collector for the reverse flotation process, effectively removing dolomite from smithsonite and reducing acid consumption in subsequent acid-leaching processes.

Sorption of U(VI) on dolomite in a dilute carbonate solution: behavior investigation and mechanism probe

Abstract The U(VI) sorption behavior on dolomite was systematically investigated in a dilute carbonate solution using batch technique. The distribution coefficients (K d) increased with the increasing time and temperature, but decreased with the increase of initial U(VI) concentration and ionic strength. As the initial pH increased from 2.0 to 10.5, the K d values first increased and then decreased, mainly due to the transition from electrostatic attraction to repulsion caused by the changes in U(VI) species. The sorption process was well-described by pseudo-second-order kinetic and Freundlich isotherm models, and was spontaneous, endothermic, heterogeneous, and pH-dependent. In the presence of HA/FA, at low pH, more HAs/FAs were adsorbed on dolomite surface, providing more sorption sites for the positively charged U(VI) species, and promoting the U(VI) sorption. At high pH, more HAs/FAs were dispersed in solution, encapsulating the negatively charged U(VI) species in aggregates, and inhibiting the U(VI) sorption. The promoting and inhibiting effects of HA on the sorption process are obviously stronger than FA. XPS spectra indicated that the surface ‒OH and CO3 2− on the hydroxylated dolomite and the –OH groups in HA/FA may be involved in U(VI) sorption. The results reported here provide valuable references for further understanding U(VI) migration in geological media.

Dolomitisation favoured by Lewis acidic background compounds in saline fluids

Predicting the type and rate of reactions between minerals and fluids is of utmost importance in many applications. Due to the presence of background ions, natural environments are often much more complex than laboratory experimental conditions that are used to derive mineral dissolution or precipitation rates. Dolomitisation is one of the most important diagenetic processes affecting carbonate rocks. Still, its underlying mechanisms are not yet completely unraveled. Here, we test the impact of background ions in saline solutions on the dolomitisation rate. Using batch reactor experiments at 200 °C and mineralogical characterisation, we demonstrate that the presence of background ions influences the fluid starting pH and specific ion effect, both impacting the dolomitisation rate. The results indicate that ions with a stronger hydration enthalpy correlate with a shorter dolomitisation induction time, and that Lewis acid AlCl3 is more effective than Brønsted acid HCl. Importantly, dolomitisation occurred at a slightly acidic pH, and carbon speciation modelling showed that carbonate ions did not dominate in any of the experiments. Hence, dolomitisation in our experiments is faster in saline, slightly acidic rather than alkaline solutions and the rate is influenced by the solution composition, with specific ion effects influencing dolomite surface charge, interfacial tension and the structure of water. These new insights have implications for interpretations on natural environments, such as deep reservoirs with saline, slightly acidic formation water, and predictions related to geological carbon dioxide storage.

Rubble Mines in the Environs of Veszprém (Bakony Region, Hungary)

In the Bakony Region, in the mines of dolomite (dolostone) surfaces between the settlements of Márkó and Pétfürdő (Várpalota), in rubble beds exposed by them and with the consideration of these, the process of rubble formation is studied here in order to interpret the characteristics of rubble beds (different thicknesses and vertical changes in grain size) in the studied area. The mines in the area (differentiated between old-school/traditional mining or mechanical mining) were classified with the consideration of mining methods. Rubble varieties were differentiated, the bedding of rubble beds was studied along profiles, and the elevation difference between mines of mechanical mining and Stream Séd was determined. The calcareous content and structure compactness of 124 samples originating from dolomite, rubble, and non-rubble in the Bakony Region were compared. The data prove that the rubble developed by dissolution. Dissolution might have been caused by both meteoric water and karstwater. The rubble of mines excavated by traditional mining mainly developed to the effect of the dissolution effect of meteoric water (the rubble beds are of coarser and coarser grain size downwards), while the mines excavated by mechanical mining were formed to the dissolution effect of karstwater (the rubble beds are coarser and coarser upwards). The formation of rubble by karstwater origin has not been mentioned in the literature yet. However, dissolution of meteoric water origin may also take place in the case of the latter, and dissolution of karstwater origin also plays a role in the development of mines excavated by traditional mining.

Transport of Ba, Sr, Cd, Pb, and As in dolomite saline aquifers injected with petroleum produced water

Predicting the transport of toxic metals in dolomite saline aquifers where petroleum produced water (PW) is commonly injected is important to prevent underground sources of drinking water contamination. This study presents new experimental results on the degree and impact of precipitation and sorption reactions on the transport of high concentrations of toxic metals (80-100 mg-Ba/L, 80-100 mg-Sr/L, 70-100 mg-Cd/L, 2-100 mg-Pb/L, and 80-100 mg-As/L) in dolomite injected with PW of variable alkalinity (0–200 mg/L), total dissolved solids (1700–77,000 mg/L), and pH (2–7). Changes in the elemental and mineral composition of dolomite surface were measured by BSEs SEM, SEM-EDS, and high-resolution XRD analyses. The results reveal a key role of alkalinity generated from the dissolution of dolomite. We show that a short initial stage where the removal of toxic metals is driven by the initial pH and alkalinity of PW is followed by a prolonged stage where the removal of toxic metals by sorption and precipitation reactions is driven by the alkalinity and pH that results from the kinetic dissolution of dolomite. Precipitated/coprecipitated metals were carbonate minerals reflecting the metal composition of PW. Attained removal levels of tested toxic metals from 1 L of PW using a dolomite core made of 200 g were >90% for Pb, >50% for As, >30% for Cd, and >5% for Ba and Sr. Apparently, the in-situ generation of alkalinity (carbonate ions) and sorption reactions of metals on dolomite catalyzes the precipitation of toxic metals as carbonate minerals. This catalytic effect of dolomite is different with PW and fresh water (FW) of low salinity (NaCl). Precipitation reactions are more prominent with FW than with PW, whereas sorption reactions are more prominent with PW than with FW.

Selective depression by using environment-friendly depressant pectin in apatite and dolomite flotation system

The difficulty of apatite and dolomite to be efficiently separated by froth flotation due to similar physical and chemical properties of both minerals in using fatty acid collectors without any depressants. In this study, pectin was explored as an efficient and environment-friendly depressant in flotation to separate apatite and dolomite. In the micro-flotation experiments, pectin displayed an intense depressing effect in dolomite flotation and slightly affected apatite flotation. Quantum chemical calculation was used to predicated the reactive site of pectin, the results demonstrated that oxygen atoms of COO, OH and COC in pectin display the most negative regions. The Zeta potential results indicated pectin was adsorbed on the dolomite surface selectively and depressed the adsorption of sodium oleate on the dolomite surface due to electrostatic repulsion effect. The Fourier transform infrared (FTIR) spectrum measurements uncovered that the selective separation of pectin was due to OH of pectin molecules. The Raman spectrum demonstrated that weak adsorption of pectin on the apatite surface was due to CO of pectin molecule, while the strong adsorption is regard as COO and COC of pectin for dolomite. XPS results indicated that COO of pectin can chelate with Ca2+ and Mg2+ of dolomite surface and depress dolomite flotation. Hence, pectin was be utilised as an eco-friendly and highly selective depressant.

Adsorption mechanism of green efficient chelating poly-L-aspartic acid in flotation separation of brucite and dolomite

Green and efficient reagents have gained considerable attention in flotation research, where poly-L-aspartic acid (PASP) is an effective reagent to realize the flotation separation of brucite and dolomite. The effect of PASP on the flotation of brucite and dolomite and its mechanism were studied using flotation tests and modern detection methods. Microflotation tests show that PASP can considerably reduce the flotation recovery of dolomite in the Sodium dodecyl sulfonate (‘SDS) system, whereas it only slightly affects the flotation recovery of brucite. Under ‘SDS, PASP can selectively reduce the contact angle of dolomite but only slightly affect that of brucite. Furthermore, atomic force microscopy detection and zeta potential tests demonstrate that PASP can strongly adsorb on the dolomite surface, considerably changing its roughness and potential value but slightly affecting brucite. The infrared spectrum analysis shows that PASP is selectively strongly adsorbed on dolomite, causing strong and weak ‘SDS adsorption on the surfaces of brucite and dolomite, respectively. Moreover, X-ray photoelectron spectroscopy demonstrates that PASP strongly impacts the Ca site of dolomite, and selective chelation of Ca is a key factor in inhibiting dolomite flotation.

Selective adsorption of the activator diammonium hydrogen phosphate in the reverse flotation separation of brucite and dolomite

To achieve efficient purification of brucite resources, diammonium hydrogen phosphate (DAP) was used as an activator to realize the reverse flotation separation of brucite and dolomite in a flotation system with dodecylamine (DDA) as the collector. The microflotation test reveals only a small difference between the flotation recovery of brucite and dolomite in the DDA system. The presence of DAP considerably improve the flotation recovery of dolomite and increase the flotation difference between the two minerals. The adsorption capacity measurements indicate that DAP selectively increase the adsorption capacity of dolomite for DDA but do not affect the adsorption capacity of brucite for DDA. Contact angle measurements reveals that DAP enhances the floatability of dolomite in DDA system and the difference in contact angle between brucite and dolomite. Zeta potential detection and Fourier transform infrared spectroscopy analysis reveal that the strong adsorption of DAP on dolomite is conducive to the adsorption of DDA on the dolomite surface but the presence of DAP do not affect the weak adsorption of DDA on the brucite surface. X-ray photoelectron spectroscopy results reveal that DAP strongly adsorbs on the characteristic Ca sites on the dolomite surface and that DDA has a strong adsorption ability on dolomite after DAP adsorption, which is beneficial for the targeted activation of dolomite flotation.

A novel depressant N,N-bis(phosphonomethyl)glycine for magnesite-dolomite separation and its mechanism

In this study a novel depressant, N,N-bis(phosphonomethyl)glycine (BPMG), is proposed for the beneficiation of magnesite from dolomite using sodium oleate (NaOL) as the collector. Laboratory flotation results show that BPMG selectively depresses the flotation of dolomite but has almost no effect on magnesite at an approximate pH of 10.0. In addition, wettability analysis reveals that differences in the NaOL adsorption characteristics due to BPMG pre-adsorption are responsible for the different flotation characteristics of the two minerals. According to the zeta potential and Fourier transform infrared spectra analysis, BPMG is adsorbed onto both magnesite and dolomite surfaces, with dolomite adsorbing strength considerably more than magnesite. Moreover, X-ray photoelectron spectroscopy results confirm that BPMG is adsorbed onto the dolomite surface by chelation between the calcium sites and the phosphonyl structure of BPMG, and on the magnesite surface by weak adsorption. As a result, BPMG is preferentially adsorbed firmly onto the dolomite surface rather than the magnesite surface. BPMG dominates the selective depression of dolomite when NaOL is used as the collector.

The separation behavior and mechanism of scheelite and dolomite using locust bean gum as depressant

Dolomite is a common vein mineral in scheelite, but how to selectively suppress dolomite in flotation of scheelite has not been addressedin the past research works. In this paper, the depressive behavior of locust bean gum (LBG) in separating scheelite from dolomite is investigated and a possible inhibition mechanism is proposed. The flotation results proved that LBG (18 mg/L) could effectively inhibit dolomite in scheelite flotation at pH = 9, and the obtained grade was 65.69 % of scheelite concentrate. Moreover, combined with the results of XPS, FTIR, Zeta potential, and contact angle experiments, it was inferred that LBG would selectively accumulate on the dolomite surface due to the presence of denser and more active action sites on the surface; and LBG could be stably adsorbed on the dolomite surface based on the stable complexation reaction between the carboxyl groups in LBG molecules and Mg2+ on the dolomite surface. Notably, the preferential adsorption of LBG not only brings a large number of hydrophilic groups to dolomite but also interference with the adsorption of sodium oleate, leading to a substantial decrease of the hydrophobicity of dolomite and finally realizing the selective inhibition of dolomite in scheelite flotation.

Experimental investigation of wettability alteration of oil-wet carbonate surfaces using engineered polymer solutions: The effect of potential determining ions ([Mg2+/ SO42−], and [Ca2+/ SO42−] ratios)

Engineered water polymer flooding (EWPF) is a promising method to improve oil recovery in carbonate reservoirs holding more than half of the world's oil reserves. It involves combining engineered water (EW) and polymer flooding (PF) to modify rock wettability, reduce mobility ratio, promote polymer stability, and lower required polymer concentration. However, limited studies addressed the simultaneous effect of engineered water compositions (i.e. potential determining ions (PDIs)) on the viscosity of polymer and wettability alteration of various carbonate surfaces. Accordingly, this study aimed to investigate the effect of salinity, PDIs, and polymer functional groups (partially hydrolyzed polyacrylamide (HPAM), and acrylamide tertiary butyl sulfonic acid (ATBs)) on the wetting properties of calcite, chalk, and dolomite surfaces as well as the viscosity of solutions at static conditions. The experimental protocol included viscosity, contact angle (CA), pH, and static adsorption tests. Two combinations of PDIs were considered in the study: [Mg2+/SO42−], and [Ca2+/SO42−]. The results revealed that the polymer becomes more tolerant to the salinity as the sulfonation degree increases, given the same molecular weight. However, at a polymer concentration of 5000 ppm, the HPAM polymer showed higher viscosity than the ATBs-based polymers, as the formation brine (FB) was diluted to 100 folds (100DFB). The tendency of shifting the wettability of carbonate surfaces towards a more water-wet state using EW and EWP treatment solutions decreased in the following order: Chalk ≥ Calcite˃ Dolomite. The study also indicates that, the wettability alteration towards favorable condition is dependent on the initial wettability of the carbonate surface. The higher level of oil-wetness detected in aged dolomite, compared with calcite and chalk, resulted in less effectiveness of EWP for dolomites. However, the low polymer interaction with dolomite surfaces indicates a positive impact on reducing polymer consumption. Moreover, the HPAM polymer was more effective in altering the wettability of dolomite towards a water-wet state compared to the ATBs-based polymer. The overall results indicate that ATBs-based polymer is a potential candidate for optimizing the effectiveness of EWPF in carbonates.

Crystal properties and interaction with flotation reagent of fluorapatite and dolomite

The difference of mineral properties is the basic condition of flotation. Studying the difference of crystal structure characteristics between fluorapatite and dolomite is helpful to understand its flotation behavior and micro-mechanism. To understand the differences in crystal and surface properties of fluorapatite and dolomite, the first-principles method based on density functional theory was used to study the crystal structure and surface properties of fluorapatite and dolomite from a microscopic perspective, and the adsorption mechanism of oleic acid ions on the surface of fluorapatite and dolomite was revealed. The results show that the activity of metal atoms in fluorapatite and dolomite crystals is different. The activity of Ca atoms in dolomite crystals is greater than that of Mg atoms. The reactivity of Ca atoms in fluorapatite crystals is low, and the reactivity of F and O atoms is high. After the surface of fluorapatite is formed, the surface of fluorapatite is mainly dominated by the fracture of F–Ca bond and O–Ca bond. The surface of dolomite is mainly dominated by the fracture of O–Ca bond and O–Mg bond. The ionicity of O–Ca bond in fluorapatite crystal is stronger, and the activity of Ca site on the surface of fluorapatite is greater than that on the surface of dolomite. The reactivity of Ca atoms on the surface of dolomite (104) is stronger than that of Mg atoms. NaOL undergoes chemical reactions on the surface of fluorapatite (001) and dolomite (104). The chemical effect of oleic acid ions on the Ca site of dolomite (104) surface is stronger than that on the Mg site. The effect of water molecules on the adsorption strength ratio of oleic acid ions on dolomite surface is less than that of water molecules on the adsorption strength of oleic acid ions on fluorapatite surface. In the absence of other conditions, the interaction strength of fluorapatite and dolomite with water molecules is similar, and the interaction between water molecules and dolomite is slightly larger than that between fluorapatite and water molecules. The effect of oleic acid ion dolomite is stronger than that of fluorapatite; the interaction between HEDP and fluorapatite is stronger than that between HEDP and dolomite.

Interface dissolution kinetics and porosity formation of calcite and dolomite (1 1 0) and (1 0 4) planes: An implication to the stability of geologic carbon sequestration

Geologic carbon sequestration (GCS) via injecting CO2 into deep carbonate reservoirs (mainly calcite and dolomite) is a promising strategy to reduce CO2 level. However, the dissolution or precipitation of calcite/dolomite planes on minerals/solution interface during long-term GCS process develops intergranular porosity and thus affects the permeability and stability of reservoirs. To investigate this process, both calcite and dolomite were dissolved in acetic and carbonic acids. A diffusion-controlled process was identified, with greater diffusion rates in acetic acid than that in carbonic acid. Quantified planes activity of both minerals follows (110) > (116) > (101) > (113) > (018) > (104) through density functional theory. Accomplished with preferential dissolution of calcite (110) planes in carbonic acid, calcite crystals precipitated with (104) planes at 423.15 K, under which, more calcite crystals were observed on dolomite surface, producing Ca-deplete surface. Molecular dynamic calculations showed higher dissolution rates of calcite/dolomite (110) planes than (104). In addition, the dissolution coefficients of Ca2+ were approximately triple of that Mg2+. Therefore, this study reveals the interface dissolution mechanisms of calcite and dolomite, especially on (110) and (104) planes at an atomic level, for the first time, providing better understanding for the stability of long-term GCS process.

Insight into the inhibition mechanism of carboxymethyl cellulose for flotation of dolomite and fluorapatite: Experimental and DFT studies

The flotation separation of dolomite and fluorapatite is difficult due to the similar surface properties. In this study, carboxymethyl cellulose (CMC) was introduced as a depressant for flotation of dolomite and fluorapatite, the adsorption mechanism of CMC on the mineral surfaces was clarified by DFT calculations, XPS analysis, zeta potential and contact angle measurements. The results showed that CMC exhibited a strong inhibitory effect for dolomite under alkaline conditions due to the surface adsorption. Compared with the adsorption of CMC on two Ca sites or two Mg sites of dolomite (104) surface, CMC preferred to simultaneously adsorb at Ca site and Mg site to form a more stable bridge adsorption, the two O in carboxyl group of CMC could bond with Ca and Mg to form chemical adsorption. However, CMC could not be adsorbed on the surface of fluorapatite, and the presence of CMC did not affect the adsorption of collector on fluorapatite surface to make it hydrophobic. Thus, CMC can be used as an alternative depressant for the selective flotation separation of dolomite and fluorapatite.

Characteristics of Adsorption/Desorption Process on Dolomite Adsorbent in the Copper(II) Removal from Aqueous Solutions.

The removal of hazardous heavy metals that have been released into the environment due to industrial activities has become an important issue in recent years. The presented study concerned the removal of copper(II) ions from aqueous solutions using dolomites. Dolomite is a very attractive adsorbent due to its wide availability, low cost, good adsorption, and environmental compatibility. The paper describes the properties of D-I and D-II dolomites from two different open-cast mines in Poland. The properties of natural adsorbents were determined based on point of zero charges (PZC), elemental analysis of the adsorbent composition, FT-IR, XRD, and SEM spectra analysis. Depending on the initial concentration of the solution used, the adsorption efficiency of copper(II) ions was 58-80% for D-I and 80-97% for D-II. The adsorption mechanism in the case of D-II dolomite was mainly based on ion exchange, while chemisorption dominated the D-I dolomite surface. Considering the possibility of the regeneration and reuse of the adsorbent, dolomite D-II is a better material (the desorption efficiency of copper(II) ions was 58-80%). The adsorption behavior of dolomites has been described using six adsorption isotherms. The best fit was obtained for the Redlich-Peterson, Jovanović, and Langmuir isotherms, indicating that monolayer adsorption occurred. The maximum adsorption capacity for copper(II) was 378 mg/g of D-I and 308 mg/g of D-II.

Recent Advances of Triglyceride Catalytic Pyrolysis via Heterogenous Dolomite Catalyst for Upgrading Biofuel Quality: A Review.

This review provides the recent advances in triglyceride catalytic pyrolysis using heterogeneous dolomite catalysts for upgrading biofuel quality. The production of high-quality renewable biofuels through catalytic cracking pyrolysis has gained significant attention due to their high hydrocarbon and volatile matter content. Unlike conventional applications that require high operational costs, long process times, hazardous material pollution, and enormous energy demand, catalytic cracking pyrolysis has overcome these challenges. The use of CaO, MgO, and activated dolomite catalysts has greatly improved the yield and quality of biofuel, reducing the acid value of bio-oil. Modifications of the activated dolomite surface through bifunctional acid-base properties also positively influenced bio-oil production and quality. Dolomite catalysts have been found to be effective in catalyzing the pyrolysis of triglycerides, which are a major component of vegetable oils and animal fats, to produce biofuels. Recent advances in the field include the use of modified dolomite catalysts to improve the activity and selectivity of the catalytic pyrolysis process. Moreover, there is also research enhancement of the synthesis and modification of dolomite catalysts in improving the performance of biofuel yield conversion. Interestingly, this synergy contribution has significantly improved the physicochemical properties of the catalysts such as the structure, surface area, porosity, stability, and bifunctional acid-base properties, which contribute to the catalytic reaction's performance.

Removal of dolomite and potassium feldspar from apatite using simultaneous flotation with a mixed cationic-anionic collector

This study aims to investigate the effect of a cationic-anionic mixed collector (dodecyltrimethyl ammonium bromide/sodium oleate (DTAB/NaOL) on the selective separation of apatite, dolomite, and potassium feldspar. Herein, several experimental methods, including flotation experiments, zeta-potential detection, microcalorimetry detection, XPS analysis and FTIR measurements, were used. The flotation tests showed that dolomite and potassium feldspar can be successfully removed from apatite simultaneously when the molar ratio of DTAB to NaOL was 2:1 with pH 4.5. Zeta-potential and microcalorimetry detection suggested that NaOL and DTAB were adsorbed on the surface of dolomite and potassium feldspar respectively, and part of NaOL and DTAB formed co-adsorption on the surface of potassium feldspar to enhance the floatability of potassium feldspar. The XPS and FTIR spectra analysis demonstrated that the cationic collector, DTAB, was first adsorbed on the surface of potassium feldspar through electrostatic attraction in the DTAB/NaOL mixture system. Subsequently, the anionic NaOL collector and cationic DTAB collector form an electron neutralisation complex, thereby resulting in co-adsorption on the surface of potassium feldspar. NaOL was chemically reacted and adsorbed on dolomite surface, but almost no collector was adsorbed on apatite surface. Finally, the adsorption models of different collectors on mineral surface were obtained.

Interaction of crude oil with halogen-free ionic liquid-based catanionic surfactants

Chemical injection has proved to have superior performance in improving oil recovery. The injected chemicals are typically designed to participate in interfacial interactions at liquid–liquid and rock-liquid interfaces while having minimum adsorption onto the rock surface. This study endeavors to investigate the interfacial activity of several environmentally-friendly halogen-free ionic liquid-based catanionic surfactants synthesized via an ion exchange reaction between cationic imidazolium-based ionic liquids, [Cnmim][Cl] (n = 4,8,12), and anionic surfactants, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and dioctyl sodium sulfosuccinate. Results revealed that the catanionic surfactant synthesized with medium-chain ionic liquid (n = 8) and sodium dodecyl sulfate exhibited higher interfacial activity, demonstrating a minimum crude oil-brine interfacial tension of 0.17 mN/m and wettability alteration index of 0.79. The results of the adsorption study also revealed the adsorption density of 2.19 mg/g onto the dolomite surface for 2000 mg/L of catanionic surfactant in seawater, which was considerably lower than cetyltrimethylammonium bromide adsorption (11.55 mg/g) in the control experiment. Finally, the surface energy analysis of liquid-rock interactions was conducted using the concept of work of adhesion to scrutinize the wettability alteration and adsorption processes, where a direct relationship between work of adhesion and adsorption density was proposed. According to the results of this study, medium chain ionic liquid-based catanionic surfactant containing dodecyl sulfate anion, exhibiting excellent interfacial activity and low adsorption tendency onto the dolomite surface, could be considered in future chemical enhanced oil recovery applications.

The application of poly (sodium 4-styrene sulfonate) as an efficient dolomite depressant in the direct flotation of apatite from dolomite

Poly (sodium 4-styrene sulfonate) was tested as a novel and efficient depressant for the selective flotation of apatite and dolomite in this work. The separation performances were evaluated and the interaction mechanisms were uncovered. Flotation results illustrated that PSS strongly depressed dolomite, while it hardly affected the flotation of apatite. Zeta potential and Fourier Transform Infrared Spectrometer results indicated that the adsorption of PSS on dolomite was more favorable than that on apatite, which impeded sodium oleate to adsorb on dolomite surface and rendered it hydrophilic. XPS results indicated that -SO3− groups of PSS strongly complexed with both Ca2+ and Mg2+ sites on dolomite surface, but PSS weakly interacted with apatite surface and hardly affected the adsorption of NaOL on apatite surface. PSS exhibited excellent selectivity and environmental compatibility, which could simplify the flotation processes in upgrading phosphate ores through one-step direct flotation.