Settling of Copper Phases in Lime Modified Iron Silicate Slag

Copper in discarded slag decreases the profits and copper recovery during the pyrometallurgical extraction processes. The copper losses to slag can be reduced by using a settling furnace, in which mechanically entrained copper droplets separate from the slag under the action of gravity. The settling rate of entrained droplets can be increased by modifying the slag composition and, thus, the slag properties, which are known to influence the settling rate. The knowledge of industrial CaO slag modification in a reduced iron silicate slag with a Fe/SiO2 ratio close to unity is limited. An industrial trial was thus conducted in an electric settling furnace, where the slag had been pretreated in a fuming furnace, to investigate the effect of CaO slag modification on the final slag copper content. Slag samples were collected from the ingoing and outgoing slag and from within the furnace of batches modified with CaO up to about 16 wt %. The trial was evaluated by comparing the final slag copper content and the copper recovery in the settling furnace. The results indicate that the settling becomes more efficient with the CaO modification as the final slag copper content decreased with increasing CaO content.

Studies on Clarification of Coal Washery Effluent Using Polymeric Flocculants and Settling Kinetics

Settling tests were conducted on the washery effluent using three types of flocculants namely cationic (Telfloc-3674F), anionic (Magna-1011) and non-ionic (Nalco-83370+). For the study purpose coal washery effluent (having pH of 8.72) was collected from a newly commissioned plant-thickener. Tests were conducted by varying the pH of the pulp at three levels of acidic (4.0), alkaline (11.0) and the natural pH (8.72) of the as collected effluent, besides the flocculent dosages varied at four levels (2, 4, 6 and 8 gpt) for each of the flocculants stated. The results of these tests, estimated in terms of initial settling rate and turbidity indicated that; among the three flocculants tested Telfloc-3674F and Magna-1011 gave best results as compared to Nalco-83370+ flocculent at a washery water pH 8.72. The effect of molecular weight of the flocculants on settling of solids in effluent has been established in terms of the kinetics with a characteristic number for each of the type of flocculants used.

Characteristics of the Coal Fines Produced from Low-Rank Coal Reservoirs and Their Wettability and Settleability in the Binchang Area, South Ordos Basin, China

By using proximate analysis, X-ray diffraction mineral analysis, scanning electron microscope, contact angle measurement, and settlement simulation experiment, the coal fines produced from the coalbed methane wells of Binchang area were used to study the characteristics including particle size distribution, composition, morphology, wettability, and settleability. The results show that the particle size of coal fines produced from coalbed methane wells are mainly >20 mesh, ranging of 1-400 μm, and the particle size distribution curve is mainly dominated by the main-secondary bimodal type, with the main peak of 30-300 μm. The particle size from large to small is drill cutting coal fines, flowback coal fines, bailing coal fines, and pipeline filter coal fines. In terms of ash content, coal fines are higher than coal seam, and drilling cuttings are higher than bailing coal fines, while the fixed carbon content of the former is lower than that of the latter. The minerals of coal fines are mainly kaolinite, illite, quartz, and other 6 minerals, and the mineral types of drilling coal fines are the most abundant, while the bailing coal fines only contain illite and quartz. The roundness of coal fine particles ranges from excellent to poor in the order of bailing coal fines, pipeline filter coal fines, flowback coal fines, and drilling cuttings. However, the sorting of drilling cuttings is excellent, and the particle edges are straight, neat, and smooth, while the sorting of bailing coal fines is poor, and the particle edges are curved, uneven, and rough. The contact angles of coal fines are 40.25°-69.5°, indicating hydrophilous. The wettability of bailing coal fines is better than that of drilling cuttings. The particle size has a negative correlation with the wettability effect. The more obvious the modification effect of positive wetting agent is, the worse the modification effect of negative wetting agent is. The modification of surfactant has nothing to do with the particle size of the coal fines, but is closely related to organic components and minerals. The larger the coal particle size, the higher the settling rate, and the higher the ash content and the lower the fixed carbon content, the faster the settling rate. With the dividing point 150 mesh, the settling rate of large particles is mainly affected by particle size, while that of small particles is affected by the composition.

Planning an experiment for cleaning exhaust gases with ultrasound

Introduction. The article deals with the protection of the environment from harmful components of the exhaust gases of a motor vehicle. In order to solve this problem, it is proposed to develop an additional device to the exhaust system of an internal combustion engine, based on the ultrasonic coagulation cleaning method.Materials and methods. Due to the need for an environmentally friendly vehicle exhaust system, an experiment is planned to determine the particle gas settling rate on the ultrasonic stand. The correct setting of the experiment requires a preliminary theoretical analysis and a reduction in the number of parameters influencing the experiment. At the time of the experiment, the number of parameters considered should reflect the main processes and their interactions fairly accurately. However, ultrasonic coagulation depends on most parameters, such as particle settling velocity, ultrasonic wave pressure, oscillation amplitude, ultrasonic frequency, particle radius, dynamic viscosity, gravity acceleration and particle mass, which can complicate and increase the time for experimentation. The method of similarity theory and dimensional analysis was used to reduce the set of variables. This method reduces the number of experiments and saves time, costs and other resources spent on the experiment with a large number of parameters.Results. As a result, a minimum number of dimensional criteria were obtained to improve the efficiency of the ultrasonic screen processing of experimental data.Conclusion. Thus, the dimensionless criteria obtained make it possible to draw up a plan for an experiment to determine the settling rate of car exhaust gas particles on an ultrasonic stand and confirm the applicability of the ultrasonic coagulation treatment method.

Studies on Clarification of Coal Washery Effluent Using Polymeric Flocculants and Settling Kinetics

Settling tests were conducted on the washery effluent using three types of flocculants namely cationic (Telfloc-3674F), anionic (Magna-1011) and non-ionic (Nalco-83370 + ). For the study purpose coal washery effluent (having pH of 8.72) was collected from a newly commissioned plant-thickener. Tests were conducted by varying the pH of the pulp at three levels of acidic (4.0), alkaline (11.0) and the natural pH (8.72) of the as collected effluent, besides the flocculent dosages varied at four levels (2, 4, 6 and 8gpt) for each of the flocculants stated. The results of these tests, estimated in terms of initial settling rate and turbidity indicated that; among the three flocculants tested Telfloc-3674F and Magna-1011 gave best results as compared to Nalco-83370 + flocculent at a washery water pH 8.72. The effect of molecular weight of the flocculants on settling of solids in effluent has been established in terms of the kinetics with a characteristic number for each of the type of flocculants used.

Using Specified Risk Materials-Based Peptides for Oil Sands Fluid Fine Tailings Management

Fluid fine tailings are produced in huge quantities by Canada’s mined oil sands industry. Due to the high colloidal stability of the contained fine solids, settling of fluid fine tailings can take hundreds of years, making the entrapped water unavailable and posing challenges to public health and the environment. This study focuses on developing value-added aggregation agents from specified risk materials (SRM), a waste protein stream from slaughterhouse industries, to achieve an improved separation of fluid fine tailings into free water and solids. Settling results using synthetic kaolinite slurries demonstrated that, though not as effective as hydrolyzed polyacrylamide, a commercial flocculant, the use of SRM-derived peptides enabled a 2-3-fold faster initial settling rate than the blank control. The pH of synthetic kaolinite tailings was observed to be slightly reduced with increasing peptides dosage in the test range (10–50 kg/ton). The experiments on diluted fluid fine tailings (as a representation of real oil sands tailings) demonstrated an optimum peptides dosage of 14 kg/ton, which resulted in a 4-fold faster initial settling rate compared to the untreated tailings. Overall, this study demonstrates the novelty and feasibility of using SRM-peptides to address intractable oil sands fluid tailings.

A numerical study of the nucleation, growth and settling of crystals from a turbulent convecting fluid

<p>We evaluate the equilibrium concentration of a thermally convecting suspension that is cooled from above and in which<br>solid crystals are self-consistently generated in the thermal boundary layer near the top. In a previous study (Patočka et<br>al., 2020), we investigated the settling rate of solid particles suspended in a highly vigorous (Ra = 10<sup>8</sup> , 10<sup>10</sup>, and 10<sup>12</sup> ),<br>finite Prandtl number (Pr = 10, 50) convection. In this follow-up study we additionally employ the model of crystal<br>generation and growth of Jarvis and Woods (1994), instead of using particles with a predefined size and density that are<br>uniformly injected into the carrier fluid.</p><p>We perform a series of numerical experiments of particle-laden thermal convection in 2D and 3D Cartesian geometry<br>using the freely available code CH4 (Calzavarini, 2019). Starting from a purely liquid phase, the solid fraction gradually<br>grows until an equilibrium is reached in which the generation of the solid phase balances the loss of crystals due to<br>sedimentation at the bottom of the fluid. For a range of predefined density contrasts of the solid phase with respect to<br>the density of the fluid (ρ<sub>p</sub> /ρ<sub>f</sub> = [0, 2]), we measure the time it takes to reach such equilibrium. Both this time and<br>the equilibrium concentration depend on the average settling rate of the particles and are thus non-trival to compute for<br>particle types that interact with the large-scale circulation of the fluid (see Patočka et al., 2020).</p><p>We apply our results to the cooling of a large volume of magma, spanning from a large magma chamber up to a<br>global magma ocean. Preliminary results indicate that, as long as particle re-entrainment is not a dominant process, the<br>separation of crystals from the fluid is an efficient process. Fractional crystallization is thus expected and the suspended<br>solid fraction is typically small, prohibiting phenomena in which the feedback of crystals on the fluid begins to govern the<br>physics of the system (e.g. Sparks et al, 1993).</p><p>References<br>Patočka V., Calzavarini E., and Tosi N.(2020). Settling of inertial particles in turbulent Rayleigh-Bénard convection.<br>Physical Review Fluids, 26(4) 883-889.</p><p>Jarvis, R. A. and Woods, A. W.(1994). The nucleation, growth and settling of crystals from a turbulently convecting<br>fluid. J. Fluid. Mech, 273 83-107.</p><p>Sparks, R., Huppert, H., Koyaguchi, T. et al (1993). Origin of modal and rhythmic igneous layering by sedimentation in<br>a convecting magma chamber. Nature, 361, 246-249.</p><p>Calzavarini, E (2019). Eulerian–Lagrangian fluid dynamics platform: The ch4-project. Software Impacts, 1, 100002.</p>

CO2 introduced the coagulation-flocculation of oil acidized wastewater: pollutant removal and cost analysis

It is difficult to adjust the pH of oil acidized wastewater rich in Ca2+, thus hindering the polyacrylamide (PAM) flocculation. This study aims at accelerating the flocculation process by introducing CO2 into the water to induce the formation of CaCO3 nuclei. The order in which CO2 and NaOH were added affected the floc structures. Compared with CO2-NaOH-PAM, the flocs of NaOH-CO2-PAM were more compact and more CaCO3 crystals were formed. The aqueous Ca2+ involved in the reaction reached 20%, and CO2 utilization was enhanced. The settling time was shortened by half (from 20 to 3 min), and NaOH consumption was reduced by one-tenth (from 0.03 to 0.003 mol), hence significantly reducing the costs. Due to the higher settling rate and shorter contact time, the NaOH-CO2-PAM flocs adsorbed less so that the residual oil was 124 mg·L−1, while in the case of CO2-NaOH-PAM it was 88 mg·L−1. As a promising coagulation aid, CO2 can also be used to mineralize pollutants in wastewater.