Phosphogypsum (PG: CaSO₄·2H₂O) is a waste product (or by-product) from the production of phosphoric acid, the main component in the production of concentrated simple and complex fertilizers. The world production of phosphogypsum exceeds 200 million tons per year. PG discharged into water bodies (seas, rivers) or disposed of in land dumps may contain elements (including heavy metals and radionuclides) in forms and concentrations that are toxic to ecosystems and human health, which raises concerns about its impact on the environment. The concentrations of these elements vary depending on the region where the raw material is mined and the process used to produce phosphoric acid. Given the significant volumes of phosphogypsum formed, an urgent problem is not only the development of methods for its disposal, but also a special, specific control over its composition after the release of PG and during its use for removal, transportation, and storage in dumps and sludge storages. This article presents the results of comprehensive studies on the determination of the chemical and mineralogical composition of by-products from an experimental plant for the processing of phosphate raw materials of the designed chemical complex of the EuroChem-Karatau company (Republic of Kazakhstan). Based on the conducted studies, it was established that, in terms of the total toxicity index, the studied wastes belong to the fourth hazard class (low-hazardous) with the possibility of processing for the purpose of their further use.

The growing demand for sustainable and renewable materials has intensified interest in agro-industrial waste as an alternative source of cellulose. This review critically examines current approaches to cellulose production from major agro-industrial residues, including cereal straw, corn residues, rice waste, sugarcane bagasse, and oilseed by-products. Emphasis is placed on the relationship between feedstock composition and extraction efficiency, highlighting how lignin distribution, hemicellulose content, and mineral impurities influence pretreatment severity, cellulose yield, and process sustainability. The review systematically analyzes chemical, enzymatic, and mechanical processing routes, with particular attention being paid to pretreatment strategies, fibrillation intensity, and yield variability. Beyond cellulose recovery, key sustainability indicators—such as energy demand, water and chemical consumption, waste generation, and chemical recovery—are evaluated to provide a system-level perspective on process efficiency. The analysis demonstrates that cellulose yield alone is an insufficient criterion for sustainable process design and must be considered alongside environmental and techno-economic metrics. Advanced applications of agro-waste-derived cellulose are discussed using a feedstock-driven approach, showing that high functional performance can often be achieved with moderately processed cellulose tailored to specific end uses. Finally, the review addresses challenges related to feedstock heterogeneity, mineral management, standardization, and industrial scale-up, underscoring the importance of biorefinery integration, closed-loop resource management, and harmonized quality descriptors. These insights provide a foundation for the development of scalable and sustainable cellulose production pathways based on agro-industrial waste.

The composition and technology for the production of semi-dry ceramic bricks using a nanostructured complex sorbent based on bentonite clay of the 11th horizon of the Tagan deposit of the Republic of Kazakhstan and basalt fiber (gabbro-diabase) of the Karauzek deposit of East Kazakhstan have been developed. The characteristics, chemical composition, and structure of the spent sorbent are given based on electron microscopic and X-ray phase analyses. A number of physical and mechanical parameters have been studied to evaluate the spent sorbent as a raw material for the production of ceramic products. The microstructures of fired ceramic samples with loam and spent sorbent have been studied, and the features of their structure have been revealed. The environmental safety of waste sorbents utilization by extraction in acidic, alkaline, and neutral media with the determination of the content of chromium, zinc, and iron ions has been studied. Experimentally obtained data indicate an insignificant concentration of chromium and zinc ions, not exceeding 3.5 µg/L. Relatively high concentrations of iron ions in ceramic bricks are associated with their high content in the feedstock and in the spent sorbent. It has been established that the introduction of the spent sorbent in the amount of 25% of the total mass increases the strength of the final product from 10.8 to 15.8 MPa, which corresponds to the M125 ceramic brick grade.

Antimony is widely used in modern science and technology. Currently, the most important consumer of high-purity antimony is the semiconductor industry.The article presents the results of the analysis of metallurgical samples for the content of antimony, which belongs to the group of harmful impurities.Traditionally, the decomposition of metallurgical samples is carried out by acid dissolution of the sample, alkali fusion or sintering. The least labor-intensive method is acid dissolution. However, this method has a number of significant disadvantages: incomplete opening, loss of antimony due to the hydrolysis of its salts, and the interfering influence of accompanying elements that also pass into solution during acidic dissolution of the sample. The most reliable results in the photometric determination of antimony content can be obtained by sintering a sample, accompanied by the separation of interfering elements by their precipitation in the form of carbonates and the transfer of antimony into a form that is not subject to hydrolysis (Me_xSb_yO_z antimonates). However, the specific conditions for the sintering process of antimony-containing metallurgical samples are not described in the literature.The work proposes a method for the decomposition of metallurgical samples, which consists of sintering the samples under study with Na₂CO₃ + ZnO. The phase composition of the presented samples has been established. A calibration characteristic for the photometric determination of antimony content in the concentration range from 1•10^-3 to 1•10^-2 mg/ml at a wavelength of 425 nm was constructed.

The study presents a comprehensive assessment of the combustion efficiency of low-grade coal from the Karazhyra deposit in small- and medium-capacity boiler units of the energy workshops operated by Vostokenergo LLP (East Kazakhstan Region, Kazakhstan). It was found that the average annual thermal energy output amounts to 2,387,348.85 GJ with a coal consumption of 164,328.5 tons. Based on operational data from 2016 to 2017, the average thermal efficiency (boiler efficiency) was 66.03%, with a maximum value of 75% recorded at the Zhezkent energy workshop. The average lower heating value (LHV) of the coal was 19.41 MJ/kg, which is below the design value of 20.52 MJ/kg, indicating the use of coal with reduced energy characteristics and elevated ash content (21.4%). The unburned carbon content in the ash and slag waste (ASW) was determined to be between 14 and 35%, indicating incomplete combustion. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed the presence of microspheres, porous granules, and coal residues, with silicon and aluminum oxides dominating the composition (up to 70.49%). Differences in the pollutant potential of ash from different boiler units were identified. Recommendations were substantiated regarding the adjustment of the air–fuel regime, modernization of combustion control systems, and utilization of ASW. The results may be used to develop measures aimed at improving the energy efficiency and environmental safety of coal-fired boiler plants.

Полимер-металл функционалды материалдары қазіргі заманғы жаңа материалды жасау үшін полимерлі модификаторды, оксидтік тасымалдағыштарды және ауыспалы металдарды біріктіру арқылы олардың құрылымдық ұйымдасуын реттеу мүмкіндігіне байланысты үлкен қызығушылық тудырады. Көп компонентті жүйелердің морфологиясы көбінесе металл компонентінің табиғатымен анықталады; дегенмен, оның мұндай материалдардың беттік ұйымдасуына әсер ету заңдылықтары одан әрі зерттеуді қажет етеді. Бұл зерттеудің мақсаты Ni-Mo-ПЭГ/Al2O3 және Co-Mo-ПЭГ/Al2O3 полимер-металл функционалды материалдарының құрылымдық және морфологиялық ерекшеліктерін зерттеу және салыстырмалы түрде бағалау болды. Материалдар полиэтиленгликольмен модификацияланған алюминий құрамдас тасымалдаушы көмегімен алынды, содан кейін тиісті металл құрамдас компоненттер енгізілді. Беттік морфология сканерлеуші электронды микроскопия, ал элементтік құрамы энергетикалық дисперсиялық рентгендік спектроскопия (EDS) көмегімен зерттелді. Екі жүйе де күрделі гетерогенді беттік ұйымдасумен және әртүрлі пішіндегі және агрегация дәрежесіндегі құрылымдық элементтердің үйлесімімен сипатталатыны анықталды. Ni-Mo-ПЭГ/Al2O3 агрегацияланған, ұсақ дисперсті және пластиналы түзілімдердің болуымен сипатталады, бұл гетерогенді беттік бедерді құрайды. Co-Mo-ПЭГ/Al2O3 созылған, ине тәрізді микротүзілімдермен толықтырылған айқынырақ пластиналы және қырлы құрылымдарды көрсетеді. EDS талдауы екі жүйеде де алюминий құрамдас негіз элементтерімен қатар мақсатты металл компоненттерінің болуын растады. Салыстырмалы талдау алу схемасын, тасымалдаушының сипатын және полимерлі модификаторды сақтай отырып, никельді кобальтпен ауыстыру материалдың беттік ұйымдасу сипатын өзгертетінін көрсетті. Алынған нәтижелер көп компонентті полимер-металл жүйелерінің морфологиялық профилін қалыптастыруда ауыспалы металл табиғатының маңызды рөлін көрсетеді. Анықталған ерекшеліктер олардың құрылымын қалыптастыратын факторлар туралы түсінікті кеңейтеді және металл компонентінің құрамын өзгерту арқылы функционалды материалдардың морфологиялық сипаттамаларын одан әрі мақсатты реттеу үшін негіз бола алады.