Caustic Alkali Research Articles

Study on Reaction Behavior and Phase Transformation Regularity of Montmorillonite in High-Calcium Sodium Aluminate Solution System

The diaspore is a typical representative of bauxite resources in China, which is the primary raw material for the Bayer process in alumina production, particularly in regions such as Shanxi, Guangxi, Guizhou, and Henan. Clarifying the phase transformations and reaction mechanisms of the silicon-containing minerals during the Bayer leaching process of diaspore is essential for improving the efficiency of alumina production. This article focuses on montmorillonite, which is one of the silicon-containing minerals of diaspore-type bauxite, investigating the reaction mechanisms and phase changes of montmorillonite under the high-calcium sodium aluminate solution system by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Magic Angle Spinning Nuclear Magnetic Resonance (MAS–NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The results show that montmorillonite dissolved and transformed into Na6(AlSiO4)6 (hydrated sodium aluminosilicate) under the high-calcium sodium aluminate solution system, and calcium oxide and sodium aluminate in the solution reacted to form (CaO)3Al2O3(H2O)6 (hydrated calcium aluminate). With the increase of reaction temperature, caustic alkali concentration (Nk), and reaction time, hydrated calcium aluminate and hydrated sodium aluminosilicate react and transform into Ca3Al2SiO4(OH)8 (hydrogarnet). Under the optimal reaction conditions of a 120 min reaction time, a temperature of 240 °C, an Nk of 240 g/L, and a CaO–to–SiO2 mass ratio (C/S) of 3.5:1, the montmorillonite reaction degree can reach a maximum of 93.71%.

From kitchen to cosmetics: Study on the physicochemical and antioxidant properties of waste cooking oil-derived soap

A large amount of used cooking oil (UCO) is improperly disposed of in sewage and rivers, leading to environmental pollution and posing health risks such as carcinogenic diseases. This study explores an eco-friendly approach to addressing this issue by repurposing UCO for laundry soap production, contributing to waste management and environmental decontamination. The soap was prepared by treating UCO with an alkaline solution (NaOH) through a simple saponification process, providing a greener alternative to traditional methods that rely on imported vegetable oils. The prepared soaps were evaluated for cleansing capacity as well as physical, chemical, and physicochemical properties. The results showed moisture content of 9.27 % to 10.34 %, pH ranging from 6.03 to 4.46, chloride percentage from 0.055 % to 0.29 %, free caustic alkali between 0.152 and 0.175, and total alkali content from 0.29 % to 0.73 %. These values meet the requirements of East African Standards (EAS), validating the quality of UCO-based soaps. By diverting UCO from waste streams and utilizing it in soap production, this approach supports waste management, minimizes environmental pollution, and contributes to sustainable production practices.

A single-step crystallization process to remove potassium from sodium aluminate solution

The high concentration of potassium in sodium aluminate solution seriously threatens the seed precipitation process and reduces the quality of alumina products, but the separation of potassium is quite difficult due to the similar chemical properties between potassium and sodium ions. In this work, a novel single-step double salt crystallization (SDSC) process with low energy consumption was proposed to remove potassium from the concentrated sodium aluminate solution using sodium sulfate, and the corresponding removal performance, kinetics and mechanism were studied. The potassium concentration decreases with the increase of additive dosage and reaction temperature, while the high caustic alkali concentration hinders the potassium removal. At 70 °C, the SDSC process exhibits a rapid crystallization and reaches an equilibrium within 60 min because of the low activation energy and weak bonding of 3 K2SO4·Na2SO4·9H2O. Under the optimum conditions, the potassium removal efficiency can achieve 85.68 %, and the potassium concentration is reduced from 120 g∙L−1 to 24.54 g⋅L−1. Finally, a cyclic utilization pathway was obtained to economically and effectively remove potassium from the sodium aluminate solution.

Low-temperature sintering of bauxite raw material with alkali as an alternative to the parallel Bayer sintering process

The aim is to develop an alternative technology of bauxite raw material processing based on low-temperature sintering of bauxite with caustic alkali, as well as to solve the issue of carbon footprint control at alumina refineries in the Urals. Laboratory tests were carried out by sintering artificial bemite and hematite with chemically pure caustic alkali at temperatures of 300, 500 and 700°C and their further leaching in weakly alkaline solutions. To study the phase, chemical, and particle size distribution of red muds after leaching, various physical and chemical methods of analysis were used, such as X-ray fluorescence, titration method, X-ray phase analysis, scanning electron microscopy, magnetometry with a vibrating sample. The Brunauer – Emmett – Teller method was used to determine the specific surface area and porosity. The study of the kinetics of the solid-phase reaction of the bemite interaction with caustic alkali has shown the kinetic interaction in the temperature range under study. Moreover, sintering of hematite at temperatures of 300 and 500°C and further leaching of the sinter with water resulted in mineralogical changes in the sludge with the production of a new mineral, maghemite, which possesses magnetic properties. When studying the magnetic properties of red mud of lowtemperature sintering of bauxite, we determined that the magnetization was as high as 19–20 electromagnetic units per g (at a sample density of 2.38 g/cm3) at a magnetic field of 10 kE. The specific surface area of these samples was 54.97 and 51.77 m2/g. The performed studies confirm that the proposed technology can be adapted for bauxite to produce highiron red slimes, thus contributing to the integrated processing of bauxite raw materials. In addition, ways to reduce carbon emissions at alumina refineries by eliminating the sintering operation with soda and limestone, which is accompanied by CO2 emission during decomposition of these compounds, can be studied.

Occupational health risk for workers in the production of synthetic polyacrylonitrile fibers

The high proportion of workers in the chemical industry working in hazardous working conditions and the justification of measures to preserve their health are an urgent task in the field of protecting the health of the working population, however, aspects of the formation of occupational risks in the production of chemical fibers remain insufficiently studied. The article presents the results of prospective cohort comprehensive studies of working conditions and health status of 137 workers in the production of polyacrylonitrile fibers. The factors of the working environment (chemical, microclimate, noise), the severity and intensity of the labor process, the first identified and chronic non-infectious morbidity for 2017–2021 were studied. It has been established that workers work under the influence of a complex of factors harmful to their health, including chemicals of hazard classes 1–4 (acrylonitrile, methyl acryate, hydrocyanide, sulfuric acid, caustic alkalis, ethylene glycol, isopropyl alcohol), industrial noise, physical and neuro-emotional overloads, the levels of which, to varying degrees, exceed the hygienic standards, forming harmful working conditions (classes 3.1–3.4). In the structure of the accumulated chronic morbidity of workers, the leading ranking places belonged to diseases of the musculoskeletal system and connective tissue (24.3 %), the circulatory system (16.04 %), and the genitourinary system (15.0 %). As a result of the assessment of cause-and-effect relationships of health disorders with work, the production conditionality of diseases of the musculoskeletal system and connective tissue, represented by dorsalgia of various levels, of an average degree (RR = 1.893; EF = 47.183 %; CI = 1.192–3.007) was established. Quantitative assessment of group occupational risk corresponded to the category of «high risk» (4.780 × 10–2), indicating the need to reduce it to an acceptable level. The limitation of the study was the study of occupational risk factors for health disorders among employees of one enterprise. The results obtained were used to develop measures to reduce occupational health risks for workers in the production of synthetic polyacrylonitrile fibers.

Physico-Chemical Parameterization of some Commercially Available Toilets and Laundry Soaps in Tansen, Palpa

Nepalese market has witnessed an impressive upsurge in the production and consumption of a variety of soaps in recent times since 2022 after covid pandemic. The physicochemical parameterization determines the quality, competency and cleaning properties of soap so that we urge sagacious use of these soaps to keep skin healthy. Due to scant knowledge about the quality of soaps, there is need to assess them. Ten parameters namely foam height, surface tension, pH, moisture content, conductance, total fatty matter, total alkali, free caustic alkali and chloride content of commercially available toilet (Dettol, Lifebuoy, Liril, Lux, No.1, Haldi Kanti, Neem Kanti and Neem Chiuri) and laundry soap (Aaha, Darshan, Dhoni and Xpert) samples collected from local market of Tansen were determined using different standard documented method of analysis. The physicochemical parameters examined in collected different soap samples are found as; foam height (20-120) ml, surface tension (38.857-67.192) dynes/cm, pH (6.67-10.54), moisture content (6.68-34.40) %, conductance (115-327) µs/cm, Total Fatty Matter or T.F.M. (42-85.10) %, total alkali (0.31-1.178) %, free caustic alkali (0.54-0.91) % and chloride content (0.1-0.69) %, indicating most of examined parameters for soap were in standard limit as quality criteria set by Bureau of Indian Standards, IS 286: 1978 except that of free caustic alkali content in laundry soaps. This study has recommended public to use toilet soap for bathing purpose as it removes dirt more and laundry soap are found to have good cleansing action for clothes.

Concept of Kshara and Its Sources in Ayurveda- A Critical Review

Kshara’ is related to ‘Paka’ (preparation) and ‘vidhi’ (application). Because of its superiority among the sharper andauxiliary instruments, caustic alkali performs excision, incision, and scarification, alleviating three doshas and being used forspecific functions. Among the para-surgical measures, all three- Agni (cauterization), Kshara (caustic alkali), and Jalauka (leeches)are important. Still, kshara is the chief because operations excision, incision, etc., cannot be performed by Agni and Jalauka. It isalso applied for specific purposes, such as in Arsha caused by Pitta. This article will be essential in containing from the smallest todeepest knowledge of Akshara, which is available in classics & articles in scattered forms. This study intends to gather allinformation related to Kshara and elaborate on their properties as mentioned in classics, especially in Sushruta Samhita andRasashashtra. The method followed here thoroughly analyzes Sushruta Samhita, its commentaries, and various research articlesthat surfed online. It is found that Sushruta Samhita explains full information regarding Kshara, types, indications, andcontraindications.In contrast, certain dravya, which are not explained as Kshara but possess Kshara properties, are also discussed.The research provides thorough literature & critical review of Kshara, its sources, and their properties which can benefit manydiseases in terms of application in different forms. In this study, the aim is to gather information about Kshara mentioned inclassics and articles. This study aims to collect information about Kshara from traditional and scholarly sources.

The synergistic effect of waste cooking oil and endod (Phytolacca dodecandra) on the production of high-grade laundry soap

A green viewpoint based on the production of soap using waste products such waste cooking oils (WCOs) and Endod (Phytolacca dodecandra) is presented. The process of saponification, which involves reacting triglycerides with fats and oils in an alkaline solution, produces soap. With the help of WCO and Endod as manufacturing inputs, this study intends to create high-quality, commercially viable eco-friendly soaps. The optimal blend of WCO and Endod with sodium hydroxide solution was used in the current investigation to create laundry soaps. Evaluations were done on the cleansing effects and physico-chemical makeup of prepared soap. As a reference control, the raw oil soaps made without and with frying were employed. The free caustic alkali content, chloride content, moisture content, ethanol-insoluble-matter, total fatty matter, pH, and foam height values of the prepared soap were found to be in the range of 0%, 0%, 16.56–22.52%, 0.1–3.05%, 63.41–75.46%, 9.22–9.82%, and 3.3–8.1 cm respectively. The results obtained by blending fried WCOs and Endod were comparable to the Physico-chemical properties of the Endod-free uncooked/fresh oil soap. The soap made by blending WCO and Endod has higher cleansing power and better lather formation than the prepared soap with WCO without Endod. Moreover, the observed data are comparable with similar data reported in other literature, recommended acceptable standards (EAS, CES), and from many countries including the British, Malaysia, and the Philippines. Cooking oils fried at different temperatures do not have much effect on the quality of soap making. This suggested that the blending of WCOs and Endod can be used as raw materials to prepare high-quality and economically feasible soaps by replacing imported oils and fats.

РАЗРАБОТКА РАЗЛИЧНЫХ ВИДОВ ЦЕМЕНТОВ ДЛЯ УСТРОЙСТВА КОНСТРУКТИВНЫХ СЛОЕВ ДОРОЖНОЙ ОДЕЖДЫ НА ОСНОВЕ АСФАЛЬТОГРАНУЛОБЕТОННЫХ СМЕСЕЙ

Today, the highway is not just a construction site, but also an important component in the structure of the country's economic development. Recently, transport loads on the structural layer of pavement have increased many times over as a result of an increase in freight turnover on the roads of the automobile network. To maintain the operational reliability of roads and extend their life cycle, high-quality and innovative materials are needed, technological modes of work adapted to them, as well as timely laboratory research, quality control and monitoring of materials being developed. This will improve the physical and mechanical properties of materials used in the construction of pavement structural layers. One effective approach is to reinforce the pavement base using cement based asphalt granular concrete mix (AGC), which involves the recycling of local materials instead of expensive stone materials. In the work, studies were carried out on the effect of a binder based on NLMK PJSC granulated blast-furnace slag, modified with various chemical additives, on the physical and mechanical properties of the asphalt granular concrete mixture. The effectiveness of the developed compositions lies in the fact that the slag becomes more hydraulically reactive not as a result of activation with caustic alkali or other low-modulus soluble silicates, but due to the use of special reagents that do not adversely affect process equipment and workers. Moreover, the annual growth of carbon dioxide emissions into the atmosphere in the production of cement expands the need for the use of alternative types of binders in construction. It has been established that samples of AGBS-K type asphalt-granular concrete mixture based on the developed compositions of an inorganic binder exceed the strength characteristics of composites using cement.

A clean two-stage Bayer process for achieving near-zero waste discharge from high-iron gibbsitic bauxite

The current Bayer process focused on alumina extraction without considering the comprehensive utilization of other valuable components, such as iron, and the resulting red mud caused severe ecological and environmental safety risks. This work proposed a clean two-stage Bayer digestion technology to obtain iron-rich red mud with low Na2O content from high-iron gibbsitic bauxite processing. The effects of digestion conditions on alumina extraction rate and iron enrichment degree in red mud were studied systematically. The ICP, XRD, SEM, and TEM were used to investigate the chemical compositions, phase structures and microstructures of bauxite and red mud. Results show that approximately 83% Al2O3 was extracted, and about 43% SiO2 was separated simultaneously in gibbsitic bauxite in the first stage, whereas undigested aluminum-bearing minerals mainly originated from substituted aluminum in goethite. Hydrogen was produced by the reaction of glycerol with sodium aluminate solution in the second stage, which promoting the reaction of Al-goethite with titanium-bearing minerals to form Fe(Ⅱ) and Ti(Ⅳ)-substituted hematite. The increase in reductants amount, caustic alkali concentration, reaction temperature, and time favored Al-goethite transformation in digestion. The total Al2O3 recovery and the Fe2O3 in red mud could reach more than 99% and 86%, respectively. Moreover, the content of Al2O3, SiO2, and Na2O in red mud satisfied the iron ore concentrate standard of GB/T 36704-2018, which was attributed to avoiding the generation of desilication products (DSP) in red mud. The 93% silicon could be removed from the liquid phase by two separations of the digested slurry. This work will facilitate the large-scale reduction of red mud discharge through further the value-added use of novel red mud technology in collaboration with steel and aluminum, achieving the green and sustainable development of the alumina industry.

Extraction of cellulose from paulownia plants and its simple ester carboxymethyl cellulose (na-kms) technology

In this experiment, Paulownia fiber plant is ground to 0.5-1 cm. In order to determine the optimum alkali solution concentration to extract cellulose from the raw material, the optimum degree of polymerization was determined by boiling in 25, 35, 50, 55 g/l solution. It can be seen from the table that certain properties of cellulose produced under the influence of different concentrations of alkali have different indicators. At alkaline concentration of 50 g/l, the cellulose yield was 49.6%, α-cellulose 89.5%, and the degree of polymerization was known in 1100 experiments. Ash content was a positive indicator of 1.78%. The scientific essence is that the cellulose is first soaked in isopropyl alcohol and mercerized in caustic alkali (NaOH) solution. Then, the alkylation process is carried out by adding a certain amount of monochloroacetic acid to the alkaline cellulose. Then, the alkylation process is carried out by adding a certain amount of monochloroacetic acid to the alkaline cellulose. The resulting carboxymethylcellulose is sent for purification. Na-CMC with 38-40% moisture content is washed in 53% ethyl alcohol and dried.

Biotechnological methods in pulp and paper production from an alternative source of raw materials - the savior of the ecosystem

The pulp and paper industry is at its peak due to the annual growth in demand for paper products which includes packaging board, hygienic paper products, printing papers and the list is endless. To date, the main source of raw materials for pulp and paper production is wood. However, its use and the use of standard flow charts in pulp and paper production creates environmental problems. For example, deforestation to obtain raw materials leads to a disruption of biogeocenoses, and technology using alkalis and acids are sources of toxic wastewater that pollute the hydrosphere and lithosphere. In order to avoid the above environmental problems, other options for sustainable sources of raw materials can be considered, such as agricultural waste - straw. By its natural origin, straw is a non-woody plant, which will significantly simplify the flow chart of pulp and paper production, on the one hand, and on the other hand, the use of straw in production will help to reduce the risks of early global warming, since most of the straw is burned in the fields. As far as toxic wastewater emissions are concerned, they can be drastically reduced through the biological degradation of straw lignin to produce pure pulp. Biodegradation of lignin can be produced by widespread wood-destroying fungi due to their ability to synthesize lignin-degrading enzymes. Thus, the use of biological agents in pulp and paper production will make it possible to eliminate the use of caustic acids and alkalis.

Catastrophic Upper Gastrointestinal Tract Complications Following Corrosive Ingestion

Ingestion of caustic substances, either acidic or alkali, is a well-known cause of significant mortality and morbidity in the pediatric and adult populations. According to the pH, physical form, amount, and rate of ingestion of these substances, a wide range of immediate as well as possible subsequent chronic complications can result. Some patients may have minimal to mild symptoms. However, others can present with moderate or even serious symptoms, in the form of dysphagia, odynophagia, hoarseness, and epigastric pain. Herein we present a case of a 26-year-old male patient with a history of Nitric acid ingestion. He initially complained of severe chest and abdominal pain, associated with hematemesis, dysphagia, odynophagia, hypersalivation, and inability to tolerate oral intake. Initial Esophagogastroduodenoscopy (EGD) showed diffuse mucosal ulceration reaching the second part of the duodenum. Multiple subsequent EGDs revealed more extensive damage and subsequent esophageal stricture and pyloric stenosis for which multiple dilatation attempts were done. The patient received extensive supportive management during his hospitalization course, but the damage was severe enough that he was referred for surgical management. Such catastrophic sequels of caustic ingestion are still encountered, especially in developing countries. We present this case looking forward to raising awareness about this dangerous phenomenon and highlighting the significance of immediate identification and grading of the injury.

Physicochemical Characteristics and Antimicrobial Efficacy of Soaps Prepared Using <i>Carica papaya</i> Extracts

Value-added products harnessing the phytotherapeutic potential of papaya are scarce. There is a paucity of data on the efficacy and safety of such products (if available) from papaya. Thus, the current study attempted to exemplify the utilization of papaya extracts in preparing a value-added product, namely, Toilet Soap. This study is the first of its kind in which the physicochemical characteristics and antimicrobial efficacy of the toilet soaps infused with different papaya extracts were assessed and compared against the market available soaps containing papaya fruit extract. The soap samples had pH values between 8.37 – 9.74 and their moisture content between 2.94 – 11.32 %. Their estimated lather volume ranged between 410 – 780 mL with good foaming power and foam stability. The laboratory-prepared soaps (Samples A to D) had matter insoluble slcohol and total fatty matter contents per Bureau of Indian Standards. They either did not contain or had an insignificant amount of free caustic alkali. The quantitative in vitro assessment findings showed antibacterial efficacy against Streptococcus aureus except for Sample E. The in vivo finger imprint test demonstrated the antibacterial efficacy of the soaps against E. coli and S. aureus.

Na2CO3 Mediated Silver Mirror Reaction of General Aldehyde at Room Temperature

The classic silver mirror reaction at room temperature in textbooks usually used glucose to react with silver nitrate and ammonium nitrate with the presence of caustic alkalis. But the aldehydes such as acetaldehyde and propionaldehyde were difficult to react under the same condition. In this paper, Na2CO3 was used to mediate the reaction instead of caustic alkalis. In a newly formed ammoniacal-silver solution, a certain dose of Na2CO3 solution and aldehydes (formaldehyde, propionaldehyde, n-butyraldehyde and glucose) were added in, and then a silver mirror formed within 2 min at room temperature without stirring or continuous shaking. This result broadened the knowledge of silver mirror reactions with aldehydes and made the scheme simple and easy, enabling the teaching to be more interesting. A survey result showed that 68.4% of preservice teachers at Anhui Normal University are willing to teach the experiment using this improved method.

The effectiveness of the new developed disinfectant in the conditions of farms for keeping animals

Disinfection methods used in industrial livestock complexes, as well as preparations are: caustic alkali, formalin, chlorine compounds, phenols. By observing the proper sanitary regime, it is possible to drastically reduce and prevent diseases and ensure the technological safety of animals. In ecological terms, they are unsafe, especially phenols, which have a relatively high stability in the external environment. The article considers an experiment to determine the effectiveness of the studied disinfectant in the conditions of a vivarium for keeping poultry. Before the experiment to determine the effectiveness of the disinfectant in the conditions of the premises for keeping poultry, a thorough washing was carried out, the premises, cages, inventory were disinfected twice with a disinfectant at a concentration of 0.25%. To control the quality of disinfection, swabs were made from various surfaces in the poultry premises in order to identify the test microorganism (E. coli), and air samples were taken in four places of the room for mycological studies. The complete absence of the test microorganism (E. coli) on the treated surfaces (floor, ceiling, left wall, right wall, rear wall) was determined, the quality of the disinfection performed complies with the regulations and is found to be satisfactory. According to the results of mycological studies of air samples in the premises of the vivarium for keeping poultry, after the use of a disinfectant the growth of mold fungi was not detected. The high bactericidal efficiency of the studied disinfectant on various surfaces with natural contamination by field strains of microorganisms, isolated before research in livestock farm conditions in a standard livestock building without the presence of animals, showed that with disinfection, including thorough mechanical cleaning and washing under pressure, followed by a double treatment of the premises with an aqueous (working) disinfectant solution at a concentration of 0.25 % at a consumption rate of 0.35 l / m2 and an exposure of 30 minutes to disinfect livestock premises, no E. coli was found on any test object.

Selective recovery of scandium with acid solutions of magnesium sulphate from ESP dust generated by bauxite sintering plants

Among potential sources of scandium and other rare earth elements (REEs) there are semiproducts generated by the alumina industry. They include red mud and ESP dust generated by sintering plants. Most of the previous research studies focused on red mud leaching using a variety of strong acids. However, because of the need to neutralize the caustic alkali present in red mud, as well as to dissolve iron and other macrocomponents, the above process is associated with a high consumption of reagents. This paper examines the possibility to selectively recover REEs from ESP dust at high pH values in the presence of magnesium cations. It is shown that the prior water leaching of ESP dust helps achieve a double rise in the REE concentration and considerably lower the concentration of Na2O in the solid residue. For selective recovery of REEs, the authors used weak solutions (pH = 2÷5) of sulphuric acid with magnesium sulphate. The latter help to desorb REEs from the surface of minerals contained in the solid residue. Over 75% Sc was recovered through solid residue leaching conducted at the temperature of 80 oC, liquid-to-solid ratio of 10:1 and duration of 60 min at pH = 2. The recovery of iron and titanium did not exceed 1–5%. With all other conditions being equal, raising pH to 3.5 would lead to a drop in the scandium recovery to 63% while the recovery of iron and titanium would drop to 0.2%. It was also found that, as the result of sulphuric acid leaching, the calcium that is present in the initial ESP dust gets precipitated in the form of gypsum and a certain amount of REEs may get carried away. This research was carried out as part of Grant No. 22-29-01515 of the Russian Science Foundation; the concentration of rare earth elements in the solid residue was determined through inductively coupled plasma mass spectrometry, supported through an assignment of the Government of the Russian Federation under Grant No. 075-03-2021-051/5.

Mechanical characteristics of Biomaterial Particles Reinforced Epoxy Resin Composites for Automobile Accessories

Abstract In this study, rattan corncob composite materials were developed and their mechanical properties were determined. This was with a view to producing alternative composite materials for automobile applications. Dried corncobs and rattan cane were crushed, treated with caustic alkali NaOH (aq) and transferred into a water bath machine to reduce the hydrophilic nature of the fibres in the polymer. The shredded corncobs and rattans cane were sun-dried after the treatment to remove the moisture content and were further pulverized and sieved to obtain 400μm particle size. Compositions of the particles were varied for seven samples with the binder kept constant at 80wt% of the whole mixture and forming them into particle panels using a metal mould. The process was repeated in order to obtain three replicates to get the exact mean value. The produced panels were tested for density, water absorption, tensile strength and modulus, flexural strength and modulus, and optical microstructure. The results revealed that the densities ranged between 1.06g/cm3 to 1.30g/cm3, the water absorption properties ranged between 0.87% to 4.55%, tensile strength ranged between 42MPa to 90MPa, tensile modulus ranged between 2.2GPa to 5.9GPa, flexural strength ranged between 50MPa to 70MPa and flexural modulus ranged between 1.5GPa to 2.7GPa. It was concluded that the developed composite materials have good mechanical properties and could serve as alternative materials for making automobile accessories like bumpers and spoilers. It could also help in solving the problem of environmental pollution caused by open burning.

ZINC COATINGS FROM ALKALINE ELECTROLYTES WITH SURFACTANTS

Alkaline-cyanide electrolytes of galvanizing have a good scattering ability, which creates conditions for obtaining high-quality zinc coatings due to the formation of soluble complexes of sodium cyanide and caustic sodium alkali, which can ensure the stability of the electrolyte and the constancy of the composition of the cyanide electrolyte. These conditions cause additional difficulties associated with regulating the composition of the electrolyte. The disadvantage of cyanide alkaline electrolytes of galvanizing is also a high sensitivity to a number of impurities in the electrolyte, the release of which is associated with difficulties. We have studied the effect of surfactants (thiourea derivative of dialkylphosphorous acids) on the scattering ability of an alkaline electrolyte capable of producing zinc coatings in the current density range of 0.5-3.5 A/dm2 , at a temperature of 20°C, with confirmation of the quality of the obtained coatings by energy dispersion and electron microscopic analysis on a JSM-6490LV scanning electron microscope with INSAEnergu energy dispersion microanalysis and HKL-Basic structural analysis with a useful magnification of 300

Production and recycling of limes in integrated mineral processing

The use of hydrochemical, biochemical, hydrometallurgical and thermochemical methods is an integral part of modern technological approaches to processing of rebellious natural and manmade raw materials. Within the framework of the hydrochemical conversion method, it becomes possible to rationalize the use of lime in the composition of middlings and waste in production of chemically precipitated calcium carbonate, which has a multipurpose purpose and is of interest for repeated and multiple use, including reduction of technology-related greenhouse gas emissions. This work presents the experimental results on soda conversion of tricalcium hydroaluminate (TCGA), which creates favorable prospects for enhancing recovery of aluminum from alkaline solutions, raising production completeness and increasing efficiency of caustic alkali turnover. The laboratory studies used highprecision process and analysis equipment, including: LabSys Evo derivatograph from Setaram, carbon analyzer of TOC-L analyzer (Shimadzu) with an attachment for measurements in solid samples SSM-5000A, single- and multi-reactor systems of parallel synthesis Auto-LAB and Auto-MATE II by HEL and others. It is found that soda conversion of TCGA proceeds at the maximum completeness at a temperature of 95 °C, total alkali concentration in the solution of 70 g/l with respect to Na2O and at the molar ratio of (Ca3Al2(OH)12)/(Na2CO3) = 1/3. These conditions ensure the alumina recovery at the level of 88–89% and the corresponding degree of TCGA conversion. The fundamental possibility of obtaining aluminate solutions with reduced caustic modulus, satisfying the conditions of their decomposition and providing the possibility of partial replenishment of caustic alkali losses in the technological cycle of alumina production, has been substantiated and experimentally proved.The research was carried out using the laboratory facilities of the Center for Collective Use and the Scientific Center for Problems of Processing Minerals and Industrial Waste of the Mining University.The study was supported by the Russian Science Foundation, R&D Grant Agreement No. 18-19-00577 date 26 April 2018.