Effect Of Grinding Time Research Articles

Investigating the grinding characteristics of vanadium-titanium iron ore tailings for sustainable utilization in cementitious material preparation

The study of the cementitious material activity of industrial solid wastes is a key issue in the comprehensive utilization of its green building materials. In this study, mechanical activation was used to prepare cementitious materials from vanadium-titanium iron ore tailings (VTIOT) as the main raw materials, and the effects of grinding time, the key parameter, on the grinding characteristics of VTIOT, the mechanical properties of the VTIOT cementitious material, and the hydration mechanism were investigated by means of surface area analysis, particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), alkali leaching, mechanical testing, hydration heat analysis, and thermogravimetric analysis (TGA). The results show that: the grinding time and specific surface area of VTIOT exhibit a linear correlation. Prolonging the grinding time, the fractal dimension of the particles gradually increases. The activity of Si4+ and Al3+ elements increases rapidly, reaching a Si4+ and Al3+ content of 96 mg·L−1 at 90 min of grinding. With a VTIOT mixing amount of 30 %, a mortar paste ratio of 1:3, and a water cement ratio of 0.5, the 50 min ground VTIOT mortar demonstrates 7 d and 28 d compressive strengths of 29 MPa and 38.7 MPa, corresponding to the highest values of the activity index, measured at 71.4 % and 75.2 %, respectively. Under standard curing conditions, the hydration products of cementitious materials at 7 d are ettringite (AFt), calcium silicate hydrate (C-S-H), alumina, ferric oxide, monsulfate (AFm), calcium hydroxide (Ca(OH)2), and calcium silica (CS). In the hydration process of 7 d, the exothermic peak and exothermic amount of the 50 min VTIOT cementitious materials are greater than those observed for other grinding times, but lower than those of pure reference cement.

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

MECHANICAL ACTIVATION OF LIZARDITE BY DRY GRINDING FOR ENHANCED MINERAL CARBONATION

Mechanical activation of Ca/Mg silicates by grinding is a pre-treatment of some mineral carbonization processes. In this study, the mechanical activation of lizardite ore from a chromite beneficiation plant waste by grinding in a stirred media mill was studied. For grinding studies, grinding times of 10-20-30 min and stirring speeds of 600-800-1000-1200 rpm were the parameters investigated, while the ball charge rate was 60% and the ore charge rate was kept constant at 40%. This way, the effects of grinding time and stirring speed on particle size distribution and energy consumption were investigated. At the end of the grinding studies, the stirring speed was determined as 1200 rpm, and the grinding time was 10 min for the finer particle size distribution (d10: 2,7 µm, d50: 13,6 µm, d90: 57.6 µm) with less energy consumption (130.4 kWh/ton). FT-IR analyses proved that the samples were dehydroxylated by the milling process. As a result, according to the analysis performed after grinding, it can be said that the finer product obtained can be used in mineral carbonation processes.

Mechanical Activation of Lizardite by Dry Grinding for Enhanced Mineral Carbonation

Mechanical activation of Ca/Mg silicates by grinding is a pre-treatment of some mineral carbonization processes. In this study, the mechanical activation of lizardite ore from a chromite beneficiation plant waste by grinding in a stirred media mill was studied. For grinding studies, grinding times of 10-20-30 min and stirring speeds of 600-800-1000-1200 rpm were the parameters investigated, while the ball charge rate was 60% and the ore charge rate was kept constant at 40%. This way, the effects of grinding time and stirring speed on particle size distribution and energy consumption were investigated. At the end of the grinding studies, the stirring speed was determined as 1200 rpm, and the grinding time was 10 min for the finer particle size distribution (d10: 2,7 µm, d50: 13,6 µm, d90: 57.6 µm) with less energy consumption (130.4 kWh/ton). FT-IR analyses proved that the samples were dehydroxylated by the milling process. As a result, according to the analysis performed after grinding, it can be said that the finer product obtained can be used in mineral carbonation processes.

Properties and microstructure development of alkali- activated coal bottom ash and titanium- extraction tailing slag binder

In this study, ground coal bottom ash (CBA) and titanium-extraction tailing slag (TS) were used as source materials to prepare alkali- activated materials (AAMs). The effects of grinding time on the properties of CBA and TS were investigated, and it was found that the optimum reactivity of CBA and TS appeared at specific surface areas of 700 ∼ 800 m2/kg. The influence of alkali content and modulus of water glass, water–solid mass (w/b) ratios and TS content on the fresh and hardening properties of AAMs were investigated. Furthermore, the reaction process of the binder was conducted by using XRD, FT-IR, SEM and hydration heat. Results showed that increasing the alkali content, reducing modulus of water glass, and adding TS into system could promote the reaction of AAM. A binder with more desirable properties was prepared at alkali content of 12%, water glass modulus of 1.2, w/b ratio of 0.45 and TS content of 20%. Its compressive strength at 7 d and 28 d was 20.8 MPa and 25.9 MPa, respectively. Microstructure analysis showed that the reaction products of binder contained AFm, N-A-S-H gel, C-S-H gel and C-A-S-H gel. This research tried to provide a fundamental basis for preparing clinker-free cement concrete from local industrial wastes to achieve sustainable development.

Effects of mechanical grinding on the physicochemical properties of silica aerogels

Mechanical grinding is a facile method to get silica aerogels (SAs) with various particle sizes. However, the relationship between the grinding parameters and physicochemical properties is still unclear. In this study, we concentrated on the effects of grinding time and grinding speed on the physical and chemical properties of silica aerogels. The results reveal that the physicochemical properties of silica aerogels are more sensitive to the grinding speed rather than the grinding time. When the grinding speed is over 200 rpm, large particles of silica aerogels are crushed into smaller particles with obviously decreasing particle sizes and the silica skeletons of silica aerogels have collapsed. The reduction of particle sizes and the collapse of skeleton lead to an increase in both the tap density and thermal conductivity. Therein, the thermal conductivity is positively proportional to the density. Furthermore, the grinded silica aerogels powders still possess the contact angles over 135°, indicating the good hydrophobicity. All these demonstrate that the mechanical grinding has evident effects on the microstructure, density, thermal conductivity and particle sizes, which further impact the performance of silica aerogels during the practical applications. Given the expanding applications of SAs across various industries, the study serves as a valuable reference for optimizing the mechanical post-treatment of SAs, facilitating the achievement of desired particle sizes. Ultimately, this research holds great potential in diversifying the application fields of SAs in their powdered form.

Mechanism of the effect of esterified modified polystyrene-maleic anhydride on the dispersion and stability of carbon black in colour paste

An aqueous carbon black slurry was prepared by esterifying polystyrene-maleic anhydride with isobutanol as the esterifying agent and using the esterified product as a dispersant for carbon black. The effects of grinding time and dispersant addition on the ground particle size of carbon black before and after the esterification modification were investigated, as well as the effect of SMA dispersant on the dispersion stability of carbon black. The carbon black slurry was investigated by introducing external conditions such as temperature and pH, and the microscopic dispersion of the ink was observed by SEM. The results showed that the dispersion effect of the isobutanol-modified SMA was stronger than that of the unmodified SMA, the particle size of the carbon black paste reached 84 nm with the best stability when the dispersant was added at 4 % and the grinding time was 120 min. FTIR and XRD results showed that the surface groups of the carbon black interacted with the groups of the dispersant to achieve dispersion stability. This study not only provides directions for the selection of dispersant for carbon black in new aqueous media but also confirms the practicality of black colour pastes in gel inks and provides a theoretical reference for the development of pigment-based gel inks.

Recovery of Carbon and Cryolite from Spent Carbon Anode Slag Using a Grinding Flotation Process Based on Mineralogical Characteristics

The aluminum electrolysis industry continually and unavoidably produces hazardous solid waste in the form of carbon anode slag. Carbon anode slag poses a serious environmental pollution risk, and it must be disposed of in a harmless manner. On the other hand, it contains a few valuable resources, as well. In order for the aluminum electrolysis industry to develop in an environmentally friendly and high-quality manner, the harmless disposal of carbon anode slag and its resourceful utilization are of considerable importance. The selective comminution of carbon and cryolite particles in carbon anode slag can be effectively achieved with grinding pretreatment. However, the optimization study of grinding process parameters has yet to be investigated. Therefore, firstly, the mineralogical characteristics and existing mode of carbon anode slag from the perspective of mineralogical properties are analyzed in this study. Then, the effects of grinding time, grinding concentration, and steel ball diameter on the particle size of the ground product (γ−0.074 mm) are investigated using response surface analysis. The results showed that the effect of grinding time was the most significant, followed by grinding concentration and steel ball diameter. In addition, the performance of the multi-stage flotation process for separating the −0.074 mm ground product was analyzed. Cryolite with a purity of 93.12% and a carbon product with an ash content of 10.67% could be simultaneously obtained through multi-stage flotation. It should be pointed out that the deep dissociation and efficient recovery of fine undissociated particles still need to be further explored.

Study on the Early Effect of Excitation Method on the Alkaline Steel Slag

The change law of alkaline steel slag cementitious activity was investigated by mechanical excitation, alkaline excitation, and salt excitation methods. The effect of grinding time, chemical activators, and content of steel slag on the properties of cement replaced by steel slag was studied. The hydration products of cement replaced by steel slag were analyzed by XRD and SEM. The results show mechanical excitation can effectively improve the particle size distribution and cementitious activity of steel slag. The best mechanical properties are obtained when grinding for 20 min and adding 10% steel slag. Chemical excitation can further improve the cementitious activity of steel slag based on mechanical stimulation. The optimal mechanical properties are obtained when the dosage of sodium hydroxide is 1.0%, the dosage of early strength agent is 2.0%, and the dosage of steel slag is 25%. The main hydration products of cement replaced by steel slag are calcite (CaCO3), calcium hydroxide (Ca(OH)2), dicalcium silicate (Ca2SiO4), and C-S-H gel. The microstructure presents a fibrous network structure, laying the foundation for improving mechanical properties.

Novel high energy media mill produced macadamia butter: Effect on the physicochemical properties, rheology, nutrient retention and application

A novel high energy media mill (HEMM) was used to prepare macadamia butter (MB). The effect of grinding time on the properties of MB was investigated. Results showed that with the grinding time increased from 0 min to 65 min, the D[3,2], D[4,3], D50 and D90 value of the MB samples were gradually decreased from 24.03, 68.48, 59.50, and 124.67 μm to 4.37, 14.25, 8.82, and 34.07 μm, respectively, and the release of volatile flavor compounds gradually increased. Moreover, it did not adversely impact the color and chemical composition. Rheological analysis showed that the viscosity and yield stress of MB gradually decreased with the increasing of grinding time and the non-Newtonian shear thinning fluid behavior (flow behavior index, n < 1) was observed. In addition, HEMM treatment result in more oil separation and poor spreadability of MB. The maximum oil separation rate reached 49.46 g/100 g after 65 min of grinding. However, the addition of 1–3 g rice bran wax/100 g can significantly improve its oil separation and spreadability in toast. The results can provide a support for the application of HEMM in MB processing, and new insights for the development of multi-purpose MB.

Experimental Study on Performance Optimization of Grouting Backfill Material Based on Mechanically Ground Coal Gangue Utilizing Urea and Quicklime.

Previously conducted studies have established that grouting backfill in mining-induced overburden bed separation and mined-out areas with broken rocks provides an efficient strategy to control strata movement and surface subsidence caused by underground mining. Grouting backfill materials (GBMs) based on coal gangue (CG) are highly desirable in coal mining for accessibility to abundant CG and urgent demand for CG disposal. However, CG is generally employed as coarse aggregate due to rather rigid and inert properties, limiting its application in GBMs. Herein, to reduce reliance on fine aggregates, such as fly ash and clay, cemented GBM formulations using ground CG powder as a dominant component were proposed. Urea and quicklime were utilized as additives to optimize slurry transportability and compressive strength. Besides typical grinding without additives, CG powder was also prepared via grinding with urea, intending to enhance the hydrogen bonding (HB) interaction between urea and minerals contained in CG. The effect of grinding time and urea on CG particle size and phase composition was investigated. Then, the dependence of slurry transportability and compressive strength on grinding time, solid concentration, urea, and quicklime dosage were revealed. It has been experimentally proved that grinding for 30~90 min significantly decreased CG particle size and even induced crystal deformation of dolomite and kaolinite. For GBMs, urea improved slurry flowability, possibly caused by decreased water absorption on the CG surface and the release of water encapsulated in hydrated cement particles. Moreover, quicklime strengthened GBM bodies, which could be explained by an accelerated pozzolanic reaction between CG powder and additional CH supplied by quicklime hydration. G60U3-based GBM-B2 with 5% quicklime provided a stable and smooth slurry with a bleeding rate of 1.25%, a slump flow of 205 mm, and a hardened body with a seven-day UCS of 1.51 MPa.

Production of Ultra-Clean Coal by the Combined Method of Grinding and Collector Gasification Flotation

The preparation and application of ultra-clean coal is one of the important aspects of clean energy technology. However, the preparation of ultra-clean coal is mainly chemical methods, which are low in efficiency, high in energy consumption and expensive. It is urgent to find an effective method to prepare ultra-clean coal. In this paper, the combined method of grinding and the collector gasification flotation method was used to obtain ultra-clean coal. The effects of grinding time on the particle size composition, mineral dissociation, surface properties and flotation results of coal samples were studied. The grinding test results show that with the increase in grinding time, the particle size and the pore diameter of coal samples decreased gradually, while the specific surface area and pore volume of coal samples gradually increased. When the grinding time was 20 min, the D90 and D[4,3] of grinding products were 5.20 um and 4.23 um, respectively. The ash content of −1.3 g/cm3 was less than 1% when the grinding time was 20 min. Compared with the traditional flotation method, the collector gasification flotation method can obtain a higher concentrate yield and lower concentrate ash content. When the amount of collector was 2.0 kg/t, the yield of clean coal obtained by the collector gasification flotation method was 4.1% higher than that by the traditional flotation method, while the ash content of clean coal was 0.3% lower.

Effect of grinding time on bismuth oxyhalides optical and morphological properties influence on photocatalytic removal of organic dye.

Herein, we reported the synthesis of BiOX (X=Cl, Br) with different grinding time like 15min and 30min to analyze the evolution of physiochemical properties and the morphological evolution. The structural, optical, vibrational properties were examined by standard characterization studies. The formation of bismuth oxyhalides were confirmed by XRD and Raman studies. The crystallite size was decreased as in 30min grinded sample whereas there is an influence of crystal structure. BiOCl (15 and 30min) samples expelled the nanoflake like structure with the flakes arranged to form a nanoflower morphology. On comparing BiOCl (15min), there is high orientation of nanoflakes on BiOCl (30min) sample. As explored in BiOBr (15 and 30min) samples, the development of nanoplates were found. The growth of nanoplates was enhanced in the better way in BiOBr (30min) than BiOBr (15min). The grinding time has explored a great influence on morphology. The photocatalyst test for prepared photocatalysts was performed to reduce the RhB dye. The photocatalysts showed 74%, 97%, 98% and 99.8% for BiOCl (15min), BiOCl (30min), BiOBr (15min) and BiOBr (30min). The rate constant value obtained was 0.008, 0.011, 0.021, 0.033 and 0.068 min-1. BiOBr (30min) sample achieved higher rate constant value. The hierarchical nanostructures and narrow bandgap has made the samples to be a potential candidate to reduce the toxic pollutants with complete efficiency.

Utilization of nanosize spent oil shale for water treatment: application of top-down nanonization technology for solid residues.

Since the dawn of nanoscience, producing nanomaterials in a simple, low-cost, and high-yield manner has been a major issue. For the commercial manufacturing of nanomaterials, various bottom-up and top-down methodologies have been established. High-energy dry ball milling is widely used for the production of diverse nanomaterials, nanograins, nanoalloys, and nanocomposites. Physical grinding of inorganic solid waste into nanosize (1-100nm) has improved their industrial applications particularly as water adsorbent. Application of nanosize spent oil shale by top-down methodology as adsorbent for phenol is addressed in the current research. The collected spent oil shale (SiO2 and Al2O3 making 45% of the material) has microstructure with average particle size of 56.6μm. The dry grinding was performed in a vibrating ball mill at various grinding time (5-150min) while keeping the grinding parameters constant including number of balls, ball size, total mass, vibration frequency, and amplitude. Upon grinding, the mean particle diameter of the bulk material was reduced to 191.8 and 85.2nm using 0.5 and 0.1mm grinding balls, respectively. The effect of grinding time on particle size and surface area was investigated; both particle size and surface area were not affected after 60min of grinding. Physical grinding by 0.1mm balls has notably improved surface area and total pore volume by 52% and 62%, respectively. Although nanosize particles (85.2nm) perform better than bulk material for phenol uptake, they underwent serious aggregation at pH > 2 and ionic strength > 1.0mM. Hence, the 191.8-nm size is selected to assess the effect of mechanical grinding on adsorption rate and equilibrium capacity for phenol as a common pollutant. Upon nanonization, adsorption rate of phenol was highly increased from 0.39 to 4.43mgg-1min-1 as analyzed by pseudo-second-order model. Adsorption isotherms were adequately presented by Sips model (prediction error 5.4-7.2%) with a maximum phenol retention capacity of 39.29mg/g after nanonization compared to 10.71mg/g for the raw material. The performance of the nanosize spent oil shale for phenol retention was promising when compared with advanced adsorbents like multiwalled carbon nanotube.

Preparation and Characterization of the Functional Properties of Synthetic Aggregates from Silico-Manganese Slag.

A large number of natural aggregates are used in the field of construction materials, resulting in the exhaustion of natural aggregates. Therefore, looking for an alternative will slow down the consumption of natural aggregates. The sintering method not only consumes a lot of energy to prepare aggregates but also produces a lot of pollutants. In this study, silico-manganese (SM) slag was dried, ground into powder, and used as raw material. Solid and liquid alkaline activator methods were used to prepare SM slag non-burning aggregate (SMNA) by the cold bonding method. The effects of grinding time, amounts of solid and liquid alkaline activators, curing temperature, and the amount of added fly ash on aggregate properties were investigated. The aggregate microstructure was characterized by XRD, SEM, and FTIR methods, and the toxic leaching analysis of aggregate was performed. The results showed that with a fixed amount of liquid activator (16.2% wt.) and solid activator (15% wt.) and fly ash (20% wt.), respectively, and curing was performed at room temperature, the aggregate properties were optimal: the bulk density of 1236.6–1476.9 kg/m3 and the water absorption lower than 4.9–5.5%. The apparent density was 1973.1–2281.6 kg/m3, and the bulk crushing strength was 24.7–27.9 MPa. The XRD, SEM, and FTIR results indicated that amorphous gel could be formed from SM under an alkaline activator, improving the aggregate strength. The results of toxic leaching showed that the aggregate prepared from SM exhibited environmentally friendly characteristics. The SMNA was obtained via the simple and low-energy consumption production process, paving the new way toward large-scale utilization of SM.

Effects of grinding time on morphology and collectorless flotation of coal particles

The impact of particle shape and surface properties has been mainly overlooked in the literature for different mineral systems. In this study, to investigate the effects of morphological variations, samples of clean coal particles (−0.212 + 0.075 mm) were used and the flotation experimental in a batch condition (2 L Denver cell) were conducted in the absence of collectors by keeping the particle size constant. Binocular microscopic images were used to determine the shape factors of coal particles. A dry ball milling process was carried out as a function of grinding time (60–960 s) and representative samples were taken for determining both shape and floatability of particles. Further, particle-bubble attachment, zeta potential, roundness, surface roughness values and flotation kinetics were measured. It was indicated that by increasing milling duration from 60 s to 960 s, the roundness and roughness increased from 0.792 to 0.809 and 23 nm to 57 nm, respectively. This led to increasing flotation rate constant from 0.4482 ± 0.02 to 0.4856 ± 0.03 1/min. In addition, the theoretical calculations for energy barrier showed that upon increasing the roughness degree from 0 to 57 nm, the energy barrier significantly decreased from 2.79E-16 to 6.51E-17 J/m2, which also proved our findings from a theoretical point of view. Thus, it was finally concluded that the more the roughness, the higher the flotation kinetics and the lower the energy barrier.

Effect of Grinding Time on the Particle Size Distribution Characteristics of Tuff Powder

We study the grinding dynamic behavior and particle size distribution (PSD) characteristics of tuff powder. With the analysis of particle size and data of activity test, the results indicate that tuff powder is easy to be ground for the coarse-grained while is difficult for the fine-grained. It is feasible to quantitatively express the milling process of tuff powder by Divas-Aliavden milling dynamic equation. The milling speed and the milling time are negatively correlated, and the grinding efficiency is minimized after 60 min. Equivalent particle size (EPS) is positively linearly correlated with the logarithm of grinding time, while specific surface area (SSA) is inversely correlated, both of them have a highly linear correlation. The PSD of tuff powder, which complies well with the Rosin-Rammler-Bennet (RRB) distribution model, has typical fractal characteristics, and its fractal dimension is also positively correlated with the milling time.

Study on maceral liberation characteristics of ball grinding and rod grinding for low-rank coal

ABSTRACT The liberation characteristics of long flame coal from the Chinese Shenhua were studied by comparison of ball grinding and rod grinding. First, the effects of grinding time on maceral liberation under the different particle size range, including vitrinite content (VC), vitrinite liberation degree (VLD) and vitrinite monomer content (VMC) were researched. Then, the influence of different grinding methods on maceral liberation were compared under same grinding fineness. Test results showed that the vitrinite in rod mill grinding is more concentrated in coarser particles compared with ball mill grinding, which provides favorable conditions for subsequent maceral beneficiation. In addition, in the range of +0.125 mm, all indexes with rod grinding are better than that of ball grinding. Especially, in the range of −0.045 mm, the vitrinite yield obtained by rod mill is always higher than that obtained by ball mill when ash content in each particle size range is almost the same. Analysis results show that the stress area of particles is small for ball grinding to result in random cracks. But rod mill crushes particles by slowly increasing squeeze force greater than stress intensity of particles, the force area of particles is larger to protect particle size decrease to a extent.

Contribution of particle morphology on flotation and aggregation of sphalerite particles

Physical properties such as particle morphology (shape and roughness) play an important role in the flotation process to understand the bubble-particle and particle–particle interactions. In this study, a new approach was suggested for the first time to correlate the aggregation and flotation of sphalerite mineral along with the contribution of morphological variations. Towards this aim, fine particles of −74 + 38 μm were produced with a ball mill while the effect of grinding time was investigated on morphology. In addition to the grinding, the roughness of particles was tuned through an abrasion treatment with silicon carbide. The shape factor of particles determined by image analysis and the roughness of particles measured with profilometer were also correlated with the micro-flotation experiments and aggregation analyses. The bubble-particle attachment time and fast-cam recordings were used to shed light on the possible mechanisms, i.e. roughness played a major role in its contribution of morphology on both flotation and aggregation of particles which were supported by fast-cam recordings as the larger bundle of particles and lower attachment time on bubble-particle attachment timer. In sum, adjusting the morphology of sulfide particles enhanced particle–particle interactions (aggregation) and led to improved bubble-particle interactions and in turn to flotation.

Experimental research on preparation of high strength concrete with rice husk ash instead of silica fume

The effect of grinding time on the properties of low-temperature rice husk ash was experimentally studied, and the feasibility of using rice husk ash instead of silica fume to prepare concrete was studied by comparison with silica fume. The results showed that the best grinding time of rice husk ash is 50 minutes, the concrete with similar properties can be prepared by replacing silica fume with super-fine rice husk ash, and the same enhancement effect can be achieved when replacing silica fume with more than 5%, and the performance was consistent.