Raw Sand Research Articles

Effect of Span-80 to Moisture Resistance of Near-infrared Curing 3D Printing Sodium Silicate Foundry Sands

In this work, a new method of near-infrared curing 3D printing sodium silicate sands (NIRC3DPSSS) driven by photovoltaic cells was proposed, and the Span-80 moisture resistance modifier was studied. NIRC3DPSSS had the advantages of high strength, rapid curing and low residual strength. However, the 24h storage strength would reduce because Na+ in the bonding bridges could absorb moisture. The experimental results showed that the strength of Span-80 modified sands molds reached 0.95MPa after 4 hours in a humidistat with 99%RH (relative humidity) containing 2.2% sodium silicate, an increase of 97.9% comparing to common sands molds. In air(80%RH), the strength reached 1.25MPa, an increase of 40.4%. The optimal effect of modification was achieved when Span-80 was 0.066% of the raw sands. Additionally, the bonding film and bridges in sodium silicate sands modified with Span-80 were more stable, smoother and free of cracks when observed using scanning electron microscopy (SEM) and energy dispersive spectroscopy(EDS).

Preparation and characterization of nanotitania@fatty acid modified quartz sand proppant with super-hydrophobic and oleophilic properties

In this work, long-chain fatty acid (lauric acid (LA), myristate acid (MA) or stearic acid (SA))@nanotantia (TiO2) composites (LATC, MATC and SATC) are applied to modify the surface of the quartz sand proppant (LATC@sand, MATC@sand, and SATC@sand proppant) to achieve excellent hydrophobic and oleophilic properties. The water contact angle (WCA) increases with increasing long chain length of the fatty acid. The WCA of SATC@sand proppant even reaches 157.9°, indicating a super-hydrophobic behavior. Moreover, after putting in boiling water for 4 hours, the SATC@sand proppant still exhibits super-hydrophobic property with WCA of 156.2°. Compared with LATC@sand and MATC@sand proppant, the SATC@sand proppant displays better thermal stability, and the thermal decomposition temperature of SATC@sand proppant is at about 170°C. Meanwhile, the SATC@sand proppant demonstrates relative lower acid solubility, bulk density (13.1 g/cm3) and apparent density (2.24 g/cm3) than raw sand proppant, indicating SATC@sand proppant shows great potential for using in hydraulic fracturing to increase petroleum production.

Characterization of different darken sand particles and behavior under fluidized and irradiated conditions

The use of solid particles in a fluidized bed with concentrated solar irradiation from the top is a promising technology for the next generation of concentrated solar power (CSP) plants. Sand is an inexpensive and abundant material easy to fluidize, but it has a low absorptivity, which is around 0.5 according to different previous works. This optical property is a key parameter for CSP applications with solid particles. This work presents a novel methodology to induce darkening of the sand surface by inducing solid state diffusion of Mn in SiO2, rendering a stable material resistant to abrasion upon the fluidization process. For this study, two different samples considering different MnCO3:SiO2 weight ratios (1:30 and 1:50) were analyzed. The objective is to compare the two samples and optimize the concentration of MnCO3 to get the desired darkening of the sand and high absorptivity. First, the main properties of the particles were analyzed (particle size, morphology, color and absorptivity). Second, the samples were tested in a lab-scale fluidized bed directly irradiated from the top with a beam-down 4kW Xe lamp. Both samples were tested under three different fluidized velocities: 1.5, 2.0, and 2.5 times the minimum fluidization velocity (Umf). In both cases, there is a significant increase in the maximum temperature reached during the process, with temperatures exceeding 260 °C. This is clearly higher than the case of raw sand, which reaches 230 °C under the same conditions. Furthermore, these values exceed the highest temperature reached by SiC in the same facility, which is 250 °C, and it is considered as one of best tested materials for CSP applications.

Suitability evaluation of selected sand geological formations for synthesis high purity crystalline silica, Iraq

This study aims determination if the sand collected from Injana and Dibdibba Formations are suitable for use as low-cost raw materials in the manufacture of high-purity crystalline silica. Sand is distributed in vast quantities within the two Formations, which occupy large portions of Iraq’s southern desert. Quartz is the predominant mineral phase, followed by calcite, feldspar, and dolomite respectively, based on mineral analysis data. SiO2 is the main oxide in sand with an average of (82.76%), (90.24%) and the rest of oxides are CaO (6.28%), (1.64%), Al2O3 (4.02%),(3.19%), Fe2O3(2.73%), (0.86%), K2O+ Na2O (2.05%), (2.51%), SO3(0.05%), (0.47%), MnO (0.01%), (0.03%) P2O2 (0.23%),(0.03%), and MgO (1.75%), (1.01%) in Injana and Dibdibba Formations respectively, which are considered as impurities impact the manufacturing properties of sand. The coprecipitation method, which produces high purity crystalline silica at a low cost, involves three steps: the first involves soaking raw sand powder in 2M HCl for 24 hours; The second involves mix purified sand with NaOH while stirring and heating it to 95C° to produce Na2SiO3; and the third involves adding 3M HCl to sodium silicate solution to produce Si(OH)4 and drying it to produce high purity of silica. The prepared silica got mineral analysis and chemical analysis. The synthesized silica was in the crystalline phase, according to the results of the mineral characterization. In synthetic silica of Injana and Dibdibba sand, The amount of SiO2 increased according to chemical analysis, reaching 96.62%, and 97.69% respectively, while all other oxides (impurities) were lowered to their lowest levels. FE-SEM revealed the existence of spherical, well-agglomerated synthetic silica particles within the size 28.6 nm and 24.76 nm in synthetic silica particles of Injana sand and Dibdibba sand respectively.

Sustainable Use of Raw Sand Residue in Production of Fired Clay Bricks

Sustainable Use of Raw Sand Residue in Production of Fired Clay Bricks

Direct synthesis of construction material from low-quality sand reacted with KOH and ethanol

A strong construction material was synthesised directly from low-quality sand (defined as the sand that particle size smaller than 250 μm) via the sol–gel method with ethanol as the solvent. Appropriate KOH content and ethanol concentration could improve the reaction degree and promote the compressive strength. The main results indicated that the specimen with 50 mass% KOH and 80 v/v% EtOH had the highest strength (>25 MPa) with the lowest porosity (5.79%). The high strength was attributed to microcline and tetraethoxysilane formation. Microcline was formed due to the dissolution and reorganization of Si-O-Si(Al) bonds in the raw sand, leading to a more homogenous structure and the decrease in the porosity. Formed tetraethoxysilane was a good consolidate, which could function as glue to further increase the strength. The carbon emission of the sand-based material in the construction phase was 233 kg CO2 eq/m2, which could be greatly reduced after reusing waste solution and utilizing waste heat. Therefore, a tough construction material was synthesised, which can partially substitute concrete, thus addressing the problem of insufficient concrete raw materials.

Biosand reactors for remediation of winery effluent in support of a circular economy and the positive effect of sand fractionation on hydraulic and operational performance

There is an extensive body of knowledge pertaining to the treatment of winery wastewater and other acidic effluents in biosand reactors. This manuscript compares the performance of biosand reactors containing raw sand and fractionated sand. Fractionation of sand (particles <0.425 mm removed) increased the hydraulic conductivity of the sand matrix 9-fold when compared to raw sand: from 0.285 mm·s−1 to 2.50 mm·s−1 and 0.129 mm·s−1 to 1.11 mm mm·s−1 before and after start-up, respectively. Similar results for both sands were obtained in terms of organic removal performance (94 % and 95 %, respectively) and neutralization of acidic (pH 4.9) winery wastewater. Results indicate that one 5.6 m3 biosand reactor module containing 2.9 m3 of fractionated sand can theoretically treat 8102 L·d−1, which is the approximate volume generated from wineries crushing 329 to 547 t of grapes per annum. This is notably higher than the design flow rate of 1000 L·d−1 in used in a pilot system containing raw sand. Furthermore, a zero-waste biosand reactor model is presented for treatment of winery wastewater. The strategy includes reuse of treated effluent for irrigation, anaerobic digestion of primary winery wastewater sludge and use of the digestate as an agricultural fertilizer, and re-purposing of the residual sand.

Effect of deposit chemistry on microbial community structure and activity: Implications for under-deposit microbial corrosion.

The deposition of solid particles carried by production fluids from oil and gas companies in horizontal surfaces of different assets has shown to cause severe localised corrosion. Sand, one of the most common deposits in the energy sector pipelines, is frequently mixed with crude, oil, asphaltenes, corrosion inhibitors, and other organic compounds. For this reason, they might favour the metabolic activity of native microbial communities. This study aimed to determine the impact of sand-deposit chemical composition on the microbial community structure and functional attributes of a multispecies consortium recovered from an oilfield and the resulting risk of under-deposit microbial corrosion of carbon steel. Sand deposits recovered from an oil pipeline were used in their raw form and compared against the same deposits exposed to heat treatment to remove organic compounds. A four-week immersion test in a bioreactor filled with synthetic produced water and a two-centimeter layer of sand was set up to assess corrosion and microbial community changes. The raw untreated deposit from the field containing hydrocarbons and treatment chemicals resulted in a more diverse microbial community than its treated counterpart. Moreover, biofilms developed in the raw sand deposit exhibited higher metabolic rates, with functional profile analysis indicating a predominance of genes associated with xenobiotics degradation. Uniform and localized corrosion were more severe in the raw sand deposit compared to the treated sand. The complex chemical composition of the untreated sand might have represented an additional source of energy and nutrients to the microbial consortium, favoring the development of different microbial genera and species. The higher corrosion rate obtained under the untreated sand suggests that MIC occurred due to syntrophic relationships between sulphate reducers or thiosulphate reducers and fermenters identified in the consortium.

Performance Evaluation of Sand Screening Machine: Effect of Sieve Size and Moisture Content

In construction industry, sand is a major raw material besides water, cement, gravel and steel. The quality of sand is vital in development of firm structures in construction. Thus, for construction industry to remain competitive, it is critical to develop efficient sand screening technologies that produce high quality sand while reducing labour cost. Therefore, the main objective of this research paper was to assess sand sieving technologies used in construction industry in Kenya and to design and evaluate performance operation of the sand screening machine that would help improve the efficiency and quality of sand while lowering the overall construction cost. The specific objectives were to design sand screening machine and to investigate the effect of moisture and sieve sizes on screening time. Experiments were conducted on semi-automatic machine driven by motor to determine fine sand produced at different moisture levels and time consumed. The machine designed consist a motor, sieve, shaft, steel hollow tubes, flat steel bars, sheet metal plates, hinges, eccentric sheaves, and angle bars. The study found that screening raw sand of 10 kg using a designed semi-automatic machine with a sieve of 3mm x 3mm and densities 1442 kg/m3, 1602 kg/m3, 1682 kg/m3, 1922 kg/m3 and 2082 kg/m3 were found to produce 8.1kg, 6.8kg, 6.1kg, 4.1kg and 2.8kg respectively with sieving time of 24s, 26s, 27s, 30s and 32s respectively. Designed semi-automatic sand sieving machine displayed a labour reduction cost of 66% leading to savings of Ksh. 39,600 per month. In addition, the output of the machine screening dry sand (1442 kg/m3) 8 hours per day was found to be 9,720 kg. In conclusion, low density sand and optimal sieve size results to high efficiency and significant labour cost savings. The study recommends the use of sand with low density (dry) and adoption of semi-automatic screening machine technologies in construction industry in order to attain Kenya’s affordable housing programme

Genesis and evaluation of heavy minerals in black sands: A case study from the southern Eastern Desert of Egypt

Black sands in the southern Eastern Desert (SED) of Egypt contain substantial reserves of heavy minerals (up to 5 %), and are found mainly in three basins namely: Hodein, Ibib and Diit between Shalateen and Halayeeb cities. The heavy minerals in these black sands include ilmenite-leucoxene (31 %–44 %), magnetite (15–18 %), zircon (11–21 %), garnet and green silicates (11–15 %), rutile (6–12 %) and monazite (2–4 %). Cassiterite, thorite, uranothorite, gold, xenotime and chromian spinel are minor quantities (<1 %). Magnetite (FeO: 75–93.5 wt%) and ilmenite (TiO2: 42.7–56.9 wt%), hosting high Mn, V, Zr, Zn, Cr, Nb and Co, were probably derived from gabbroic rocks. The detrital chromian spinel composition (Cr#, 0.51–0.61; Mg#, 0.5–0.63; TiO2 < 1.0 wt%) and its morphology are similar to those of spinels in fore-arc peridotites from the SED of Egypt, suggesting dominance of fore-arc basins for peridotite emplacement. These basins were formed during arc-arc or arc-oceanic crust collision and encolsed ophiolites, gabbroic rocks and I-type granites as sources of the SED black sands. The studied garnets are mostly almandine in composition with few grossularite and spessartine; they might have been derived from I-type granites and gneisses sources. The rutile and monazite show enriched LREE relative to HREE, and display marked defeciency in Eu, suggesting highly fractionated granitic rocks as a main source. Two distinct types of zircon are recorded: radioactive (Hf: 1578–8770, Y: 319–1335, U: 36–114 and Th: 40–64 ppm) and non radioactive (Hf: 427, Y: 44, U: 2 and Th: 2 ppm); they were probably derived from different granitic sources. Compositions and P-T conditions (T: 655–970 °C, P: 1.18–9.53 kbar) of magmatic amphiboles are similar to those derived from I-type granitoids. Bulk analyses of the economic heavy mineral assemblages show significant concentrations of Fe (393 kg/ton), Zr (183 kg/ton) and Ti (129 kg/ton) with minor Cr (14 kg/ton), Ba (7 kg/ton), Hf (4.9 kg/ton), Th (up to 3.34 kg/ton) and U (0.29 kg/ton). The elevated contents of Th and U could be related to the occurrence of monazite and zircon with subordinate thorite, uranothorite and xenotime. The total REE contents of these bulk analyses range from 1 to 4 kg/ton, where LREEs form 80–90 % of total REEs. Monazite (ΣREEs: 443604 ppm on average), garnet, zicon (ΣREEs: 421 ppm) and rutile (ΣREEs: 309 ppm) are the main host of REEs in the investigated black sands. Tonnages of raw sands, to a depth of one meter, are estimated per 10 km2 in each basin, giving 18 million tons for Ibib basin and 19 million tons for both Diit and Hodein basins. Economic heavy minerals constitute 6–26 % of the total heavy minerals and around 1.0 % of total raw sands. Calculated reserves of these economic minerals, per 10 km2 of black sands, range from 0.1 million ton in Ibib and Hodein basins to 0.2 million ton in the Diit basin.

Structural, Chemical and Magnetic Characterization of Quartz Sand from Cluj Area, Romania for Future Beneficiation in the Glass Industry.

For use in crystal glass production, quartz sand must contain less than 0.09% iron. If the sand contains more than 0.09% Fe, the iron must be removed. In the present study, quartz sand from tailings ponds near the Cluj area of Romania is analyzed for potential use in the glass industry, after magnetic separation. The particle size distribution of raw sand was determined, and mineralogical analyses was realized. Using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), morphology and elemental distribution maps on the particle was performed. The evolution of the iron content versus the particle size was analyzed. Using X-ray diffraction, the phases occurring in the sand were investigated in relation to the particle size. Magnetic separation with two magnets, having different energy, was performed for identifying the phases attached to the magnetic particles. Magnetic hysteresis measurements evidenced complex and multiple iron phase behavior.

Planning of Optimal Raw Materials Inventory Using the Marcov Chain Method

Inventory is an important issue to control. Both finished goods and raw material inventories are the same with ingredient raw for the production process . no seldom our find problem where company no To do good control _ in management inventory that results in needs customer no fulfilled . Ray Traso Jaya is company that manufactures and sells paving block products , bataco , riol concrete and pits wind where in the production process experience disturbance in carry out the production process caused level management supply ingredient raw sand and cement that are not optimal as a result company difficulty for Fulfill needs customers who are fluctuating . Formulas problem in study this is " How " determine supply ingredient raw materials and costs supply ingredient optimal raw material at Sinar Traso Jaya?”. Study this aim for determine supply ingredient optimal raw material and cost supply ingredient optimal raw . Method analysis used _ in research this is method Analysis Calculation With Markov Chain. Where is the result study this company can adapt costs required at the time level booking with ingredient fluctuating standard _ with notice stock ingredient available raw . _ That is if ingredient raw sand initial 0 or stock empty on level ordering 170.638 kg the optimal cost is at Rp. 1300,000 , if ingredient cement raw 0 or stock empty on level booking as much as 57,617 kg with the optimal cost is IDR 1,300,000.

Experimental study of different coatings on silica sand in a directly irradiated fluidised bed: Thermal behaviour and cycling analysis

The present work shows the experimental results obtained with sand particles, which where coated to increase the thermal absorptivity for CSP applications. The particles were tested in a lab-scale fluidised bed with concentrated irradiation on the top. The experimental results indicates that two of the three coatings tested, based on graphite and carbon black, worked properly and absorbed between 30 and 40% more energy than raw sand due to the higher thermal absorptivity. Both coatings were also experimentally tested during 10 cycles of charging/discharging without apparent deterioration of their thermal properties. Sand coated with graphite exhibited colour change, from an initial dark black to a greyish tone that did not have an impact on the particles thermal response. The extrapolation of the results observed at lab-scale, to the maximum expected temperatures in new generation of CSP plants with solid particles, up to 1250 K, shows that coated particles may enhance the energy effectively stored in the bed by 60–80% compared to raw sand.

Effect of Particle Character and Calcite Dissolution on the Hydraulic Conductivity and Longevity of Biosand Filters Treating Winery and Other Acidic Effluents

Acidic effluent such as winery wastewater is challenging to remediate. Biological sand reactors can simultaneously remove organics and neutralize winery wastewater via biotic and abiotic mechanisms. The systems have been shown to be suitable for treating the intermittent flow of wastewater at small wineries. It has been shown that dissolution of calcite is the most important abiotic mechanism for increasing the pH of the influent. In this study, sand column experiments were used to determine the effects of (i) sand particle size distribution on calcite dissolution kinetics, and (ii) the effects of calcite particle dissolution on the hydraulic conductivity. The results were then used to calculate the theoretical temporal abiotic neutralization capacity of biological sand reactors with differently sized sand fractions, including unfractionated (raw) sand. The results were compared with those determined from a pilot system treating winery wastewater over a period of 3 years. Sand fractions with larger particles contained lower amounts of calcite (using Ca as a proxy), but exhibited higher hydraulic conductivities (3.0 ± 0.05 %Ca and 2.57 to 2.75 mm·s−1, respectively) than those containing smaller particles and/or raw sand (4.8 ± 0.04 to 6.8 ± 0.03 %Ca and 0.19 to 1.25 mm·s−1, respectively). The theoretical abiotic neutralization capacity of biological sand reactors was compared with a pilot system with the same flow rates, and a temporal abiotic neutralization capacity of 37 years was calculated for biological sand reactors, which compared favorably with the theoretical results obtained for wastewater with pH values between 2 (8.2 years) and 3 (82 years). It was concluded that biological sand filters with around 10% calcite will be able to abiotically neutralize winery wastewater and other wastewaters with similar acidities for the projected life span of the system. Future work should focus on determining the effect of sand grain size on the bioremediation capacity, as well as the use of biological sand reactors for treating other acidic organic wastewaters such as fruit processing, food production and distillery wastewater.

Breathing-Focused Yoga Intervention on Respiratory Decline in Chronically Pesticide-Exposed Farmers: A Randomized Controlled Trial.

BackgroundOccupational exposure to pesticides has been associated with lung and cognitive function exacerbations. In the present study, we tested the effectiveness of breathing focused yoga intervention on alleviation of adverse respiratory and cognitive effects associated with chronic pesticide exposure in farmers.MethodsWe undertook a parallel, two-armed randomized controlled trial with blinded outcome assessors on a chronically pesticide-exposed farming population. The study was conducted at district Panipat, State Haryana located in the Northern part of India from November 2019 to August 2020. A total of 634 farmers were screened, and 140 farmers were randomized to breathing-focused yoga intervention (BFY, n = 70) and waitlist control arms (n = 65). BFY was delivered weekly in 45-min group sessions over 12 weeks followed by home-based practice. The primary outcome was the change in spirometry-based markers of pulmonary function from baseline expressed as raw values, Global Lung Initiative (GLI) percent predicted (pp), and GLI z-scores after 24 weeks of intervention. Secondary variables were Trail making tests (TMT A and B), Digit symbol substitution (DSST), and WHO Quality of life-BREF (WHOQOL-Bref). Analysis was by intention-to-treat. Mediation analysis was done considering oxidative stress markers as potential mediators.ResultsAt the end of 6 months of intervention, the overall follow-up in the participants was 87.85% (n = 123); 90% (n = 63) in the control group, and 85.71% in the yoga group (n = 60). The mean age of the study cohort (n = 140) was 38.75 (SD = 7.50) years. Compared with the control group, at 24 weeks post-intervention, the BFY group had significantly improved status of the raw sand z scores markers of airway obstruction, after adjusting for confounders, FEV1, FVC, FEF25-75 [z score-adjusted mean differences (95% CI); 1.66 (1.10–2.21) 1.88 (1.21–2.55), and 6.85 (5.12–8.57), respectively. A fraction of FEF25-75 change (mediation percentage 23.95%) was explained by glutathione augmentation. There were also significant improvements in cognitive scores of DSST, TMT-A and TMT-B, and WHOQOL-Bref.ConclusionIn conclusion, regular practice of BFY could improve the exacerbations in the markers of airway obstruction in chronically pesticide-exposed farmers and cognitive variables. A significant mediating effect of glutathione augmentation was also observed concerning the effect of the intervention on FEF25-75. These findings provide an important piece of beneficial evidence of the breathing-based yoga intervention that needs validation across different farming ethnicities.Clinical Trial Registration:www.ClinicalTrials.gov, identifier: CTRI/2019/11/021989.

Resilience and sturdiness of the foundry sand as a result of the partial substitution of cement and fine aggregate

Foundry sand is a superior quality silica sand byproduct of the refractories metal casting industries. Because of its great heat conductivity, it has been utilised as a moulding casting material for millennia. Raw sand is utilised in a variety of foundry procedures, and different binders and admixtures are applied to it to improve its characteristics. For the foundry sector, experiment sand is no longer acceptable. The goal of this experiment is to determine the chemical characteristics of foundry sand, as well as the optimal replacement ratios for foundry sand as a fine aggregate: 10%, 20%, 30%, and 40%. For self-compaction, a super plasticizer is also added. Finally, the strength characteristics of foundry sand-formed concrete are identified. The experiment aims to provide the same strength as regular concrete. Experimentation leads to the research of beam strength characteristics. Experimentation leads to further study of concrete's pesticide and mechanical characteristics. The strength properties like compressive strength, split tensile and flexural strength is improved upto -%,-% and % for 20% substitution of foundry sand added mix. The better performance were observed at early ages of curing. The resistance against acid attack will be allowable upto 20% substitution of foundry sand. The usage of foundry sand will be eco-friendly and scalable for product making in products.

Simultaneously achieving high-effective oil-water separation and filter media regeneration by facile and highly hydrophobic sand coating

Efficient oil-water separation, including of emulsified oil separation, is one of the problems restricting the green development of the petrochemical industry. Herein, highly hydrophobic sand was fabricated in one-step, followed by an investigation of adsorption capacity for various oils of hexane, petroleum ether, diesel, tetrachloroethylene and tetrachloromethane. The modified sand (MS) filter bed was subsequently set up to investigate the oil separation efficiency for oil-water mixtures, emulsions and actual petroleum refinery wastewater, respectively. Moreover, the capture process of the oil droplet by the MS was observed by a high-speed camera system, and the oil removal mechanism was explored. The removal feasibility of the oil adhered to the MS in a hydrocyclone was also investigated. The oil could be quickly adsorbed by the MS, and the adsorption capacity was positively correlated with oil density. A high flux of 14,436 L·m−2·h−1 and a considerable separation efficiency of 99% were obtained when the MS was applied for oil-water mixture separation. Additionally, the highest separation efficiency of various emulsions was up to 99.3%. Regrading actual petroleum refinery wastewater, the oil removal efficiency of the MS reached 90% rather than 57.8% of raw sand. The oil droplets in the wastewater were efficiently separated by the MS based on the mechanism of adsorption and coalescence. Additionally, the oil adhered on the MS could be removed, and the oil concentration decreased from 17.6% to 5.2%, which was ascribed to the MS spinning in a hydrocyclone. A novel oil-water separation method of hydrocyclone-intensified filtration by facile and highly hydrophobic sand coating was proposed, and simultaneously the filter media can be effectively regenerated. It is believed that this work might provide a low cost, recyclable and efficient strategy for oil removal, which shows high promise for industrial oily wastewater treatment.

Migration characteristics of atrazine in porous media during managed aquifer recharge

Abstract To study the influences of sand and gravel layer and groundwater velocity of Yufuhe River on atrazine migration, adsorption-desorption and sand column experiments were carried out. Results show that the adsorption capacity of montmorillonite, raw sand and washed sand to atrazine sequentially weakens. In different media, the time for atrazine concentrations to peak in washed sand with montmorillonite (WSM), raw sand and washed sand is 60, 135 and 105 minutes respectively, and the peak concentration accounts for 84, 90 and 95% of the initial concentrations. Under different flow rates, the peak time in washed sand at flow rates of 100, 150 and 200 mL/min is 135, 105 and 75 minutes, and the peak time in WSM is 90, 60 and 45 minutes, respectively. Results from this study indicate that increasing flow velocity and suspended colloids concentrations can promote the migration of atrazine in aquifers, while the presence of clay minerals in sand and gravel layers can reduce atrazine migration. Thus, during Yellow River water recharging, the sand and gravel layer of Yufuhe River is helpful to protect the aquifer, but the colloids-associated migration of atrazine can contaminate groundwater in underlying karst aquifer.

Innovation comprehensive solutions for off-gases cleaning in steel industry. Technical solutions for dusty gas flows cleaning

Metallurgical production associates with such processes as crushing, drying and pneumatic transportation of raw materials, roasting, melting etc., in the process of which hard particles and harmful gaseous components are emitted into atmosphere. At pneumatic transportation of raw materials and sand, their concentration in the atmosphere as a rule exceeds maximum permissible concentrations. Existing facilities of dusty flows cleaning in some cases don’t ensure sanitary norms ГН 2.1.6.3492‒17. Technical solutions proposed to clean gases in a centrifugal filter, a facility of complex gas cleaning – cyclo-filter and two-stage system of high-concentrated gas-dust flows cleaning. Description of the centrifugal filter, cyclo-filter, two-stage facility of gas cleaning design presented. The facility comprises centrifugal filter and ceramic pulse filter. Industrial tests of the centrifugal filter ЦФ2-6-1 under conditions of a system of pneumatic transportation of sand established, that efficiency of gas-dust flows cleaning of sand particles in a six-channel filter can reach 98.65%. Application of two-stage system of gas cleaning comprising centrifugal filter and ceramic pulse filter ФКИ enables to reach residual hard particles concentration at the exit of such a facility of 5 mg/m3, having initial dust level of 127878 mg/m3. Application of such a complex two-stage cleaning facility allows to reach values of 0.1 of maximum permissible concentrations near the source of emissions.

Comparison of the melting properties of glass substrates for thin film transistor liquid crystal display and organic light-emitting diode

ABSTRACT The melting properties of two kinds of glass substrates for thin film transistor liquid crystal display (TFT-LCD) and organic light-emitting diode (OLED) were investigated. Chemical reaction process of the batches was similar for two substrates determined by DSC-TG test. The ascending behavior of bubbles with different fining agents of two substrates were studied by High-temperature imaging observation (HTO) test. Viscosity and surface tension for the glass melt were investigated. The results showed that tin dioxide (SnO2) exhibited better fining effect than stannous oxide (SnO), both for TFT-LCD and OLED substrates. For OLED substrate, it took more time to approximate the steady state for fining process due to its higher viscosity and higher surface tension. The molten resistance of these two substrates was also determined, which could provide some reference for the design of electrode in mass production. And the effect of grain size distribution of main raw material silica sand on the melting quality of bulk glass samples was also developed. Silica sand with 150–200 mesh exhibited the best melting and fining effect.