Acidic Slurry Research Articles

Effects of sulfation on the flotation capacity of oleic acid in the dolomite and fluorapatite system: A combined experimental and DFT study

Dolomite cannot be efficiently separated from fluorapatite (FA) by oleic acid in an acidic slurry, due to the poor collecting ability of oleic acid. In this work, sulfation was used to improve the flotation performance of oleic acid. Flotation tests showed that the sulfating collector exhibited stronger flotation ability for dolomite. However, the H2SO4-treated FA could not be floated by the sulfating collector. The solubility of the sulfating collector at pH 4.5 was higher than that of HOL at the same pH. Thus, more sulfating molecules and anions were generated in the collector solution, which accounted for the high flotation efficiency of the sulfating reagent. The sulfating collector molecule and anion could adsorb on the H2SO4-treated dolomite surface. Moreover, the reaction of the sulfating collector anions with the dolomite surface generated alkyl Mg/Ca salts.Furthermore, DFT calculations were employed to evaluate the interactions of the sulfating reagent with the H2SO4-treated dolomite surface. The sulfation produced two isomers. The most stable isomer, i.e., 10-sulfooxy stearic acid (SOA), was used in the calculations. The SOA anion could vertically or paralelly adsorb onto the dolomite. The parallel structure was more stable, where the COO− and OSO3− groups of SOA anion bonded with two metal atoms on the dolomite surface. These findings suggest that the sulfation collector is suitable for the reverse flotation of collophane.

Experimental study on single crystal diamond CMP based on Fenton reaction and analysis of oxidation mechanism

Single crystal diamond (SCD) is an ultra-hard semiconductor material with exceptional chemical inertness, posing challenges for conventional oxidants to induce oxidation. The highly electronegative and potent ·OH produced by the Fenton reaction possesses significant importance in enabling efficient and high-quality polishing of SCD. This study delved into optimizing the Fenton reaction polishing slurry through orthogonal experiments and explored its influence on SCD CMP concerning various mechanical factors. Findings indicated that pH value, Fe3O4 concentration, and H2O2 concentration had a significant impact on the material removal rate (MRR) and surface roughness of SCD CMP, with Fe3O4 particle size playing a comparatively minor role. The optimized Fenton reaction polishing slurry achieved a peak MRR of 742.7 nm/h and a minimum surface roughness Ra of 0.240 nm. The acidic Fenton reaction polishing slurry generated H+ and ·OH, which interacted with the surface of SCD, forming an oxidation layer consisting of C–O/C–H and CO groups, thereby facilitating SCD material removal. This study provides a theoretical basis for the broader application of the Fenton reaction in SCD CMP at scale.

Erosion wear characteristics of metal seal floating ball valve in gas–solid–liquid three-phase flow

During high-pressure acid leaching, sulfuric acid slurry acts as the transportation medium in the withdrawal drum for acid pressure leaching. Over time, the metal-sealed float valve at the pipeline outlet may experience internal leakage. To address this issue, the Euler–Lagrange method for fluid dynamics is used to evaluate the corrosion wear characteristics of the valve in a three-phase flow. Specifically, we investigate the erosion and wear properties of the ball valve core as it opened and closed. To further understand how different ball valve openings impact erosion characteristics, we establish a correlation between the corrosion rate and the drag coefficient. Our research findings indicate that as the valve’s relative opening decreases from 80% to 20%, the corrosion wear rate gradually increases. In addition, the number of particles within the valve cavity also follows a similar trend. These erosion results highlight the significant influence that particle quantity has on erosion. Moreover, with an increase in particle size, both the erosion gradient range and maximum erosion rate decrease.

Synthesis and Surface properties of AOS Based detergents: A Green Synthetic approach

A novel sustainable AOS-based biodegradable detergent was produced and its physical properties were investigated. The functional metrics of detergent performance are equivalent to, and sometimes better than, commercial samples such as Surf Excel. The detergent formulations based on AOS are made with the least amount of Sodium Tripolyphosphate, Sodium Lauryl Sulphate, and acid slurry, which are utilized in excess commercial samples and contribute to pollution. All of these samples had good performance in terms of surface tension decrease, foam volume, and viscosity.

Synthesis and Surface properties of LABSA Based detergents: An Ecofriendly Approach

A novel ecofriendly LABSA based biodegradable detergent were synthesized and their physical properties were studied. The functional parameters of detergents performance are comparable and sometimes better than commercial sample ex. Surf excel. The formulations of detergent based on LABSA based formulated using least proportion of Sodium Tripolyphosphate, Sodium Lauryl Sulphate and acid slurry which are used in excess commercial samples leading to pollution. All these samples had shown excellent performance in terms of surface tension reduction, foam volume and viscosity.

Effect of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) on Cu/Ta chemical mechanical planarization (CMP) in the barrier layer: A novel complexing agent and the dual role on Cu

Tantalum and its nitrides are used in barrier layers in copper interconnected ultra-large-scale integrated circuits. However, due to the different physical and chemical properties of copper (Cu) and tantalum (Ta), the difference in removal rates is a problem. This study developed an acidic barrier layer slurry with better Cu/Ta rate-selective properties. During the research and development process, it is found that the introduced novel complexing agent, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), has a bisexual effect on Cu while effectively enhancing the Ta removal rate. Therefore, the detailed analysis was carried out on the mechanism of PBTCA on Cu/Ta. In this study, the effects of the slurry fundamental composition, include pH value, oxidant H2O2 and complexing agent PBTCA, on Cu/Ta removal rate were firstly investigated by electrochemical and chemical mechanical planarization (CMP) experiments. Subsequently, XPS, SEM and AFM tests were utilized for in-depth analysis of the micro-activity mechanism of PBTCA. The concentration of PBTCA between 0.2 wt% and 0.3 wt% was found to have complexation effect on Cu, and the concentration between 0.3 wt% and 0.8 wt% was found to have corrosion inhibition effect on Cu, which verified that PBTCA has a dual effect on Cu. This phenomenon effectively reduces the difference of Cu/Ta removal rate and facilitates surface flattening. In addition, PBTCA is an environmentally friendly and biodegradable organophosphate condensate. Finally, the slurry stability experiments were carried out by average particle size and zeta potential tests. CMP experiments and atomic force microscopy (AFM) tests were employed to verify the performance of the slurry. It was concluded that the slurry was well stabilized with the oxidant addition, and the storage time had almost no effect on the removal rate and surface morphology of Cu and Ta. The results of the study provide a feasible method for barrier layer CMP.

Study of phosphoric acid slurry rheological behavior in the attack reactor and development of a model to control its viscosity using artificial intelligence

This work aims to determine the rheological properties of the industrial phosphoric acid slurry and its behavior under the operating conditions of the phosphoric acid production process. For that, several experimental tests on the slurry were carried out, using a Rheometer (Anton Paar), which testing the effect of temperature and solid content. The results show that, for a fixed solids rate, the viscosity of the slurry decreases with temperatures from 75°C to 82°C and increases for temperatures above 82°C considered as the maximum temperature required by the process. This phenomenon is due to the morphological change of the gypsum which corresponds to the range of calcium sulfate hemihydrate formation. For a fixed temperature, the viscosity increases with increasing slurry solid content (31% to 37%). The viscosity increases with the shear gradient. Increasing the solid charge in the slurry increases its resistance to flow and movement. Thus, the slurry has a higher tendency to settle. A comparative study of four rheological models, Casson, Bingham, Ostwald and Herschel-Buckley, led to the selection of the Herschel-Bulkley model. This predicts the behavior of the phosphate slurry with a correlation coefficient of 99.9% and a MAE less than 4%. Overall, the results show that the threshold flow of the slurry is negligible, and its behavior is nonlinear. Thus, the slurry is a non-Newtonian fluid, with a dilatant rheological behavior. The various tests carried out enabled us to measure the viscosity of the phosphoric acid suspension for different solids contents and at different temperatures. The results obtained enabled us to study the rheological behavior and develop an artificial neural network model to control the viscosity of the slurry at the phosphoric acid attack tank.

Experimental analysis on thermal energy storage performance of micro-encapsulated stearic acid and stearyl alcohol PCM slurries; A comparative study

This study examined the thermal performance of a slurry containing micro-encapsulated phase change materials (me-PCMs) for thermal energy storage (TES) applications such as solar thermal or PVT systems. Specifically, the study focused on stearic acid (SAC) and stearyl alcohol (SAL) as the phase change materials, dispersed within an ethylene glycol aqueous solution. The research revealed that increasing the concentration of PCM in the slurry led to improved latent heat energies for both micro-encapsulated stearic acid (me-SAC) and micro-encapsulated stearyl alcohol (me-SAL) slurries during melting and solidification processes. Moreover, me-SAL slurries exhibited higher latent heat energies compared to me-SAC slurries at the same concentrations. The addition of CTAB surfactant positively influenced the stability of the slurry dispersion, ensuring a more even distribution of me-PCMs within the base fluid. These findings highlight the potential of me-SAC and me-SAL slurries as effective materials for TES applications. Significantly, me-SAL slurries outperformed me-SAC slurries in TES performance due to their greater latent heat energies during melting and solidification.

Copper recovery from waste printed circuit boards by NH3−(NH4)2S2O8–CuSO4 slurry electrolysis

The recovery of waste printed circuit boards (WPCBs) is always at the center of the issue of e-waste, and even “urban mining”. Slurry electrolysis has been certified as a new and efficient approach for directly recovering copper from WPCBs, although its current efficiency is not high. Therefore, an alkaline slurry electrolysis system with NH3−(NH4)2S2O8–CuSO4 was examined to improve the current efficiency because (NH4)2S2O8 produces SO4-· or ·OH in an alkaline environment. Factors such as the current density, concentration of NH3·H2O, (NH4)2S2O8, NaCl, and Cu2+, solid/liquid (S/L) ratio, and electrolysis time are discussed. The results showed that the NH3−(NH4)2S2O8–CuSO4 electrolyte could significantly impact the current efficiency and copper recovery rate. Under optimum conditions (4 mol/L ammonium hydroxide, 1 mol/L ammonium persulfate, 20 g/L copper ion(Ⅱ), 0.5 mol/L sodium chloride, S/L ratio of 30 g/L, 20 mA/cm2, and 3 h), the copper recovery rate was 90.10%, and the copper current density was significantly improved to 83.03%, which was considerably higher than that of the acidic slurry electrolysis system (approximately 70%). Because copper in the WPCBs and Cu2+ can form [Cu(NH3)2]+ with ammonia and ammonia persulfate, it is substantially easier to electrodeposit than [Cu(NH3)4]2+. Meanwhile, the purity of the obtained copper foil was > 99.986%, meeting the standard for commercial cathodic copper, and markedly higher than that of the acidic slurry electrolysis system. Thus, alkaline slurry electrolysis shows great potential for applications in the e-waste industry.

Understanding the interaction between erosion and corrosion of pipeline steel in acid solution of different pH

The pure corrosion, erosion-corrosion and pure erosion behaviors of X65 pipeline steel in acid NaCl solution of different pH levels (ranging from 1.5 to 5.0) were studied using a rotation disc system, aiming to understand the interaction between erosion and corrosion of pipeline steel operating in acid slurry. The corrosion and erosion-corrosion performances of the steel were electrochemically measured in conjunction with surface characterizations. The pure erosion performance was studied by applying cathodic protection to eliminate the corrosion component. The propagation of the localized erosion-corrosion at different pH levels were probed using wire beam electrode. Results show that pH = 3.5 is a critical value for the transition of cathodic reaction under erosion-corrosion. In the acid fluids of pH < 3.5, the reduction of H+ is the main cathodic reaction, leading to a general erosion-corrosion feature with scattered small pits, which are initiated from the inclusions. Negative erosion-enhanced corrosion (E-C) is found at pH < 3.5 due to the wear of Fe3C networks. The oxygen reduction becomes the main cathodic reaction in the acid slurry of pH ≥ 3.5, resulting in the formation of erosion-corrosion pits and craters. The removal of the rust layer would result in positive E-C performance at pH > 3.5. Significant localized erosion-corrosion would occur at pH ≥ 3.5, where fixed major anodic sites are visualized. Obvious erosion-corrosion pits and craters would form with the occurrence of oxygen reduction. More serious corrosion-enhanced erosion (C-E) prefers to occur at the pitting areas where high macro-cell currents are registered.

Preparation and properties of hydrotalcite-foamed magnesium phosphate cement for fire protection of steel structures

Foamed magnesium phosphate cement (MPC) is prepared for the fire protection of steel structures based on the carbonate decomposition reaction of hydrotalcite in acidic MPC paste. Hydrotalcite decomposes in an acidic MPC slurry to generate CO2, and approximately 50% of the theoretical gas generation remains in the MPC slurry to form foamed MPC with an apparent density of < 650 kg/m3 and 1-d compressive strength of > 4.0 MPa. The actual gas production of hydrotalcite in the MPC slurry gradually increases as the hydrotalcite content increases and the M/P ratio decreases. The fine hydrotalcite particles refine the pores and obstruct the paths between them, resulting in closed and uniform pores. When the thickness of the foamed MPC coating on the steel plate surface is only 6.0 mm, the temperature on the steel plate back after being subjected a 60 min fire resistance test is about 400 °C, which is significantly lower than the critical temperature (538 °C) for the steel structure to remain stable after encountering fire. Foamed MPC exhibits excellent fireproofing performance owing to its high porosity, low thermal conductivity, the release of CO2 in the pores, and the dehydration of hydration products, which retards heat transfer in case of fire.

Experimental study on three additives used for the removal of nitrite, a byproduct of ozone oxidation denitration technology

Nitrogen oxides resulting from fossil fuel combustion are one of the major atmospheric pollutants. Ozone oxidation flue gas denitration technology has garnered significant attention for its benefits such as high efficiency, low temperature and simultaneous removal of multiple pollutants. However, the large amount of nitrite in the absorption products makes it prone to secondary pollution. A cost-effective and harmless treatment of the by-product nitrite will promote the ozone oxidation denitration technology. This study focused on investigating three different additives (ammonium chloride, ammonium carbonate, and urea) that can be added to react with nitrite and remove it in a harmless way. The effects of reaction temperature, initial nitrite ion concentration, reaction molar ratio, and initial pH on nitrite removal efficiency were explored. Combined with a wet spraying system, the synergistic removal of NOx/SO2 and by-product nitrite has also been studied. The experimental results revealed that with appropriate operating conditions and additives, the by-product nitrite can be efficiently removed while the system can achieve efficient removal of NOx/SO2. Among the three additives, ammonium carbonate was found to have the best overall removal effect. However, urea had an advantage over the other two additives in highly acidic and low-temperature slurry.

Evaluation of erosion–corrosion process of Ti(C, N)-based cermets in acidic SiO2 slurry

This study investigates the erosion-corrosion process of Ti(C, N)-based cermets and compares it with WC-based cemented carbides in acidic SiO2 slurry. During the process, corrosion pits caused by corrosion expose the hard phase's sharp corners. The exposed corners crack, break and form debris due to the impact of SiO2's erosion. The slurry washes away the debris, and further corrodes the pits. Eventually, the binder surrounding the hard phase is destroyed, and the hard phase peels off due to the lack of bonding. In the initial stage, chemical corrosion is the main mode of destruction, followed by mechanical erosion. As the erosion time increases, the volume loss rate of cermets and cemented carbides also increases. The volume loss rate of medium-grained cemented carbide is the highest, followed by submicron-grained cemented carbide, and the smallest for the cermet. The erosion effect of SiO2 particles was more significant than the corrosion effects on volume loss in acidic SiO2 slurry.

MAS NMR and DFT study of electrochemical performance of silicon nanoparticle as anodes for Li-ion batteries

In this work we have investigated the effect of slurry pH on the lithiation mechanism of silicon nanoparticle (SiNP) anodes in lithium-ion batteries. To this end, we have used a combination of lithium (7Li) and silicon (29Si) magic angle spinning nuclear magnetic resonance (MAS NMR), density functional theory (DFT), and electrochemical charge–discharge cycling. The NMR results show that different lithiation mechanisms are present depending on the pH. An acidic slurry facilitates the lithiation of SiNP, whereas a basic slurry oxidises the SiNP to form a shell of SiO/SiO2, which must be cracked before Si lithiation becomes relevant. In a basic slurry, the leading process during the first cycle is the reaction of Li+ and SiO/SiO2 to form lithium silicates. Consequently, this intermediate step leads to a greater capacity loss in the basic media than in the acidic one.

Efficient machine learning model to predict dynamic viscosity in phosphoric acid production

The rheological behavior of the phosphoric acid slurry, during the production process, strongly depends on its dynamic viscosity. Controlling this property limits P2O5 losses, minimizes energy consumption and ensures optimal flow conditions. Thus, reliable simulation tools predicting the viscosity property are needed for analysis and process optimization. To this end, three machine learning (ML) methods: single-layer artificial neural network (ANN), gradient boosting (GB) and random forest (RF), were tested using 456 data of dynamic viscosity at different solid content, shear rate and temperature, obtained from industry. The performance of these models was evaluated and compared using diverse precision metrics. The GB has shown to be the outperforming model with determination coefficient greater than 99%, and Root Mean Squared Error lower than 0.750, on both training and validation datasets. Based on the importance of the explanatory variables, all models agree on the large effect of solid content on dynamic viscosity, followed by shear rate, then temperature. The GB relative partial dependence diagram made it possible to deduce operating intervals for the solid content of the pulp to be fed to the phosphoric acid reactor, leading to optimal flow of the suspension at the level of the attack and maturation units.

Research on the Chemical Mechanical Polishing Process of Aluminum Alloy Wafers with Acidic Slurry

Aluminum alloy has low density, good thermal conductivity, and low resistivity, which has been widely used in the fields of the defense industry, aerospace, and machinery manufacturing. As technology advances, there is a growing demand for high-precision parts and green processing. In this paper, a green chemical mechanical polishing (CMP) slurry for aluminum alloy is developed to optimize the rotational speed and pressure and improve the quality of polished aluminum alloy surface. The influence of CMP slurry composition on the quality of aluminum alloy surface and its mechanism are analyzed. Orthogonal experiments and single-factor experiments are used to investigate the effects of CMP slurry composition and process parameters on the surface quality of polished aluminum alloy. A green chemical mechanical polishing slurry consisting of deionized water, 6 wt.% SiO2, 2 wt.% H2O2, and citric acid to adjust pH=3 was proposed, with the pressure of 24 kPa and rotational speed of 90 r/min. After the CMP of aluminum alloy, surface roughness was reduced from 45.587 nm to 0.876 nm in the scan range of 70 μm × 50 μm. The mechanism was analyzed by X-ray photoelectron spectroscopy (XPS).

The wear behaviour of different metallic bond alloys tested in a modified B611-13 test in an acidic, neutral and alkaline media

The abrasive and adhesive wear behaviour of metallic bonds can be significantly affected by varying pH values of the attacking medium. However, the knowledge about the pH value influence on diamond impregnated bits used in core drilling industry is still limited. One recent publication shows the advantage of modifying a standard ASTM B611-13 test to investigate the abrasive and adhesive wear behaviour of a diamond segment bond material in a neutral regime (pH7). This study mainly focuses on the effects of a varying surrounding media on the tribological behaviour using an acidic, neutral and alkaline slurry. This emulates more aggressive conditions for the diamond segments used in mining as well as construction industry. The pH value at which such diamond segments operate can differ from pH2 up to a value of pH13. The present work studies the wear behaviour of two metallic bonds in a modified B611-13 arrangement at 4 m/s sliding speed and different pH values. The tested specimens are investigated with regard to their change in mass and microstructure at the sliding interface zone. The results reveal a significant influence of the pH value on the wear behaviour of the bond system.

Effect of Acidic Hydrogen Peroxide and Lysine Slurry on Ovonic Threshold Switch Film in Chemical Mechanical Polishing

For improving the three-dimensional structure of phase-change memory devices, Ovonic threshold switch devices have received renewed attention as selectors owing to a simple production process, good scalability, and excellent performance. It can replace transistors and diodes in the available technology. In this article, we studied the GeSe-based chemical mechanical polishing process. The different concentrations of hydrogen peroxide and lysine interacting with GeSe in chemical mechanical polishing were investigated. Material characterization was performed by scanning electron microscopy and atomic force microscopy. In addition, the reaction mechanism in the chemical mechanical polishing process was analyzed by electrochemical experiments and X-ray photoelectron spectroscopy.

Study on Construction and Reinforcement Technology of Dolomite Sanding Tunnel

The No. 2 conduit of the Xiaopu Tunnel in the Yuxi section of central Yunnan’s water diversion project is taken as the research object, starting from the geological conditions along with the characteristics, formation mechanism and evolutionary model of dolomite sanding. This paper discusses the engineering problems of the project’s tunnels with dolomite sanding in the water-rich section, and its corresponding engineering reinforcement plan. It was found that in the tunnel section with normal level of dolomite sanding, there was no water seepage, where measures such as advanced small conduit, mechanical excavation, short grubbing and strong support could all be adopted for safe passage. Even in the water seepage section of the weak dolomite sanding tunnel, the surrounding rock was found in close interlock with strong self-stability. The excavation and support were implemented according to the category of normal surrounding rock. In the water-rich sections with strong and intense dolomite sanding, gushing of water and sand were quite frequent, with developed fissures, broken rock masses and rich waters. During the engineering operation, phosphoric acid and sodium silicate slurry in addition to urea formaldehyde resin and oxalic acid slurry plus Malisan and liquid catalyst slurry were first prepared for water plugging. Then, pure water slurry was used for surrounding rock reinforcement, which exerted an excellent effect. This method can provide reference for reinforcing tunnels of sandy dolomite in other areas of projects.

The effect of process parameters on chemical mechanical polishing of quartz glass

The effects of polishing pressure, polishing speed and pH value of the polishing slurry on the chemical activity of quartz glass, the material removal rate (MRR) and surface roughness (Ra) of the workpiece were studied. Using MRR and Ra as evaluation indexes, three factors and four levels of the orthogonal test were used to perform chemical mechanical polishing on quartz glass. By measuring the contact angle between the polishing slurry and workpiece, the influence of different polishing slurries on the chemical activity of quartz glass surface was studied. The processing mechanism of CMP quartz glass was analyzed. The order of important factors affecting MRR of quartz glass was: pressure [Formula: see text] rotation speed [Formula: see text] pH value; the order of significant factors affecting Ra of quartz glass was: pressure [Formula: see text] pH value [Formula: see text] rotation speed. The optimum polishing process parameter combination of the MRR was: pressure 27.58 kPa, rotation speed 85 rpm, pH value 12; the optimum polishing process parameter combination of the Ra was: pressure 13.79 kPa, rotation speed 85 rpm, pH value 12. The MRR and Ra of the workpiece are evaluated from the mechanical action of pressure and speed and the chemical action of polishing slurry on the workpiece. The results proved that the effect of the alkaline polishing solution on MRR and Ra of quartz glass is more significant than that of the acidic polishing slurry.