Scaled-up laboratory research into dry magnetic separation of the Zhezdinsky concentrating mill tailings in Kazakhstan

Purpose. Development of the rational technology for processing manganese-bearing tailings of the Zhezdinsky concentrating mill in the Republic of Kazakhstan aimed to obtaining manganese concentrate for smelting the silicomanganese. Methods. An integrated methodology of research is used in the work, which includes an analysis of modern scientific developments and the experience of their use by mining-and-metallurgical enterprises. Experimental study of the tailings material composition has been made. A research scheme has been drawn up, including dry re-grinding of the mature tailings from concentrating mill with subsequent air classification, the products of which are beneficiated by means of dry magnetic separation in a separator with a constant strong magnetic field. Granulometric and fractional compositions of the feedstock and separation products have been studied. Findings. Based on the granulometric and fractional composition analysis of the Zhezdinsky concentrating mill mature tailings, it has been determined that the manganese minerals contained in them are very finely disseminated and belong to easily beneficiated materials. For a more complete recovery of manganese into the concentrate, dry re-grinding and air classification techniques have been included in the beneficiation scheme. Scaled-up laboratory research on tailings beneficiation has been conducted under the scheme: dry grinding to a grain-size of less than 1 mm, screening with division into classes of 0.5-1.0 mm and 0.0-0.5 mm, and then air classification. Air classification products are beneficiated using dry magnetic separation. It has been revealed that the use of air classification during the magnetic field induction of 0.5 T allows to increase the magnetic fractions yield by 7.5% and the manganese recovery by 9.42%. Analysis of the magnetic separation results of fine classes indicates the possibility of obtaining manganese concentrate with the required quality even without using the air classification. This greatly simplifies the beneficiation scheme for mature manganese-bearing tailings at the Zhezdinsky concentrating mill. Originality. It has been determined that dry re-grinding of the concentrating mill mature tailings to a grain-size of less than 1 mm, followed by air classification, makes it possible to fully disclose the manganese minerals. With subsequent dry magnetic separation this leads to an increase in the magnetic fraction yield and in the manganese recovery. Practical implications. The optimal technology development enables obtaining manganese concentrate with the required quality for the subsequent production of ferromanganese or silicomanganese during metallurgical treatment.Мета. Розробка раціональної технології переробки марганцевовмісних хвостів Жездінської збагачувальної фабрики республіки Казахстан для отримання марганцевого концентрату для виплавки силікомарганцю. Методика. У роботі використовувалася комплексна методика досліджень, що включає аналіз сучасних наукових розробок і досвіду їх використання гірничо-металургійними підприємствами. Проведено експериментальні дослідження речового складу хвостів. Складено схему дослідження, що включає сухе доподрібнення лежалих хвостів збагачувальної фабрики з наступною повітряною сепарацією, продукти якої збагачуються методом сухої магнітної сепарації у сепараторі з постійним сильним магнітним полем. Вивчено гранулометричний та фракційний склади вихідної сировини й продуктів сепарації. Результати. На основі аналізу гранулометричного та фракційного складу лежалих хвостів Жездінської збагачувальної фабрики встановлено, що мінерали марганцю, що містяться в них, дуже тонковкраплені й відносяться до легкозбагачуваних матеріалів. Для більш повного вилучення марганцю в концентрат у схему збагачення були включені операції сухого доподрібнення й повітряної сепарації. Проведено укрупнено-лабораторні дослідження збагачення хвостів за схемою: сухе подрібнення до крупності менше 1 мм, просіювання з поділом на класи 0.5-1.0 і 0.0-0.5 мм, які надходять на повітряну сепарацію. Продукти повітряної сепарації збагачуються сухою магнітною сепарацією. Встановлено, що застосування повітряної сепарації при індукції магнітного поля 0.5 Тл дозволяє підвищити вихід магнітної фракцій на 7.5% і збільшить витяг марганцю на 9.42%. Аналіз результатів магнітної сепарації тонких класів вказав на можливість отримання марганцевого концентрату необхідної якості навіть без застосування повітряної сепарації. Це значно спрощує схему збагачення лежалих марганцевовмісних хвостів Жездінської збагачувальної фабрики. Наукова новизна. Встановлено, що сухе доподрібнення лежалих хвостів збагачувальної фабрики до крупності менше 1 мм, з подальшою повітряною сепарацією, дозволяє повністю розкрити мінерали марганцю, що призводить при подальшій сухій магнітній сепарації до підвищення виходу магнітної фракції та збільшення вилучення в ній марганцю. Практична значимість. Розробка оптимальної технології дозволяє отримати марганцевий концентрат необхідної якості для подальшого отримання в металургійному переділі феро- або силікомарганцю.Цель. Разработка рациональной технологии переработки марганецсодержащих хвостов Жездинской обогатительной фабрики республики Казахстан для получения марганцевого концентрата для выплавки силикомарганца. Методика. В работе использовалась комплексная методика исследований, включающая анализ современных научных разработок и опыта их использования горно-металлургическими предприятиями. Проведены экспериментальные исследования вещественного состава хвостов. Составлена схема исследования, включающая сухое доизмельчение лежалых хвостов обогатительной фабрики с последующей воздушной сепарацией, продукты которой обогащаются методом сухой магнитной сепарации в сепараторе с постоянным сильным магнитным полем. Изучены гранулометрический и фракционный составы исходного сырья и продуктов сепарации. Результаты. На основе анализа гранулометрического и фракционного состава лежалых хвостов Жездинской обогатительной фабрики установлено, что содержащиеся в них минералы марганца весьма тонковкрапленны и относятся к легкообогатимым материалам. Для более полного извлечения марганца в концентрат в схему обогащения были включены операции сухого доизмельчения и воздушной сепарация. Проведены укрупнено-лабораторные исследования обогащения хвостов по схеме: сухое измельчение до крупности менее 1 мм, грохочение с разделением на классы 0.5-1.0 и 0.0-0.5 мм, которые поступают на воздушную сепарацию. Продукты воздушной сепарации обогащаются сухой магнитной сепарацией. Установлено, что применение воздушной сепарации при индукции магнитного поля 0.5 Тл позволяет повысить выход магнитной фракций на 7.5% и увеличит извлечение марганца на 9.42%. Анализ результатов магнитной сепарации тонких классов указал на возможность получения марганцевого концентрата требуемого качества даже без применения воздушной сепарации. Это значительно упрощает схему обогащения лежалых марганецсодержащих хвостов Жездинской обогатительной фабрики. Научная новизна. Установлено, что сухое доизмельчение лежалых хвостов обогатительной фабрики до крупности менее 1 мм, с последующей воздушной сепарацией, позволяет полностью раскрыть минералы марганца, что приводит при последующей сухой магнитной сепарации к повышению выхода магнитной фракции и увеличению извлечения в ней марганца. Практическая значимость. Разработка оптимальной технологии позволяет получить марганцевый концентрат требуемого качества для последующего получения в металлургическом переделе ферро- или силикомарганца.This research has been performed with financial support from the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan under grant No. AR05136152, “Development of technology for processing technological mineral formation of manganese-bearing tailings of the Zhezdinsky concentrating mill”. We express our gratitude to the scientific team of the Ore concentration laboratory at the branch of the Zh. Abishev Chemical-Metallurgical Institute of the republican state enterprise “National Centre on Complex Processing of Mineral Raw Materials of the Republic of Kazakhstan” for rendering a qualified assistance when conducting research

APPLICATION OF MICROWAVES FOR THERMAL EOR METHODS

Heavy oil reservoirs represent about 70% of the total oil reservoirs. EOR methods must be applied due to the low primary recovery of heavy oil reservoirs. The low primary recovery of these reservoirs is based on the viscosity of the heavy oil. Thermal EOR methods are the best to apply to extract more heavy oil. On-site combustion, gravity drainage with steam, and cyclic steam injection are the most famous thermal EOR methods. However, there will always be a demand for more productive methods of improving production with lower usage costs. Moreover, the growing concern about the environmental component of oil production may prompt the need to look for more suitable and profitable ways. One of these methods is electromagnetic heating, which can be even more efficient. This study compared the microwave heating method with the conventional thermal method. The effects of the microwave heating method on the viscosity of heavy oil and temperature alteration were analyzed. In addition, the effects of microwave power and water saturation were investigated on the impact of production efficiency using the experiment. From the experimental results, the microwave heating method gave better results in viscosity reduction. Overall, a higher power level showed a higher temperature alteration with a higher reduction in viscosity. In addition, higher water saturation gave higher results in temperature; however, from the efficiency side, the best choice for water saturation was identified, which is 10%

Synthesis of 5-Hydroxyectoine from Ectoine: Crystal Structure of the Non-Heme Iron(II) and 2-Oxoglutarate-Dependent Dioxygenase EctD

As a response to high osmolality, many microorganisms synthesize various types of compatible solutes. These organic osmolytes aid in offsetting the detrimental effects of low water activity on cell physiology. One of these compatible solutes is ectoine. A sub-group of the ectoine producer's enzymatically convert this tetrahydropyrimidine into a hydroxylated derivative, 5-hydroxyectoine. This compound also functions as an effective osmostress protectant and compatible solute but it possesses properties that differ in several aspects from those of ectoine. The enzyme responsible for ectoine hydroxylation (EctD) is a member of the non-heme iron(II)-containing and 2-oxoglutarate-dependent dioxygenases (EC 1.14.11). These enzymes couple the decarboxylation of 2-oxoglutarate with the formation of a high-energy ferryl-oxo intermediate to catalyze the oxidation of the bound organic substrate. We report here the crystal structure of the ectoine hydroxylase EctD from the moderate halophile Virgibacillus salexigens in complex with Fe3+ at a resolution of 1.85 Å. Like other non-heme iron(II) and 2-oxoglutarate dependent dioxygenases, the core of the EctD structure consists of a double-stranded β-helix forming the main portion of the active-site of the enzyme. The positioning of the iron ligand in the active-site of EctD is mediated by an evolutionarily conserved 2-His-1-carboxylate iron-binding motif. The side chains of the three residues forming this iron-binding site protrude into a deep cavity in the EctD structure that also harbours the 2-oxoglutarate co-substrate-binding site. Database searches revealed a widespread occurrence of EctD-type proteins in members of the Bacteria but only in a single representative of the Archaea, the marine crenarchaeon Nitrosopumilus maritimus. The EctD crystal structure reported here can serve as a template to guide further biochemical and structural studies of this biotechnologically interesting enzyme family

Value-Added Products from Natural Gas Using Fermentation Processes: Products from Natural Gas Using Fermentation Processes, Part 2

Methanotrophic bacteria can use methane as their only energy and carbon source, and they can be deployed to manufacture a broad range of value-added materials, from single-cell protein (SCP) for feed and food applications over biopolymers, such as polyhydroxybutyrate (PHB), to value-added building blocks and chemicals. SCP can replace fish meal and soy for fish (aquacultures), chicken, and other feed applications, and also become a replacement for meat after suitable treatment, as a sustainable alternative protein. Polyhydroxyalkanoates (PHA) like PHB are a possible alternative to fossil-based thermoplastics. With ongoing and increasing pressure toward decarbonization in many industries, one can assume that natural gas consumption for combustion will decline. Methanotrophic upgrading of natural gas to valuable products is poised to become a very attractive option for owners of natural gas resources, regardless of whether they are connected to the gas grids. If all required protein, (bio) plastics, and chemicals were made from natural gas, only 7, 12, 16–32%, and in total only 35–51%, respectively, of the annual production volume would be required. Also, that volume of methane could be sourced from renewable resources. Scalability will be the decisive factor in the circular and biobased economy transition, and it is methanotrophic fermentation that can close that gap

Value-Added Products from Natural Gas Using Fermentation Processes: Fermentation of Natural Gas as Valorization Route, Part 1

Methanotrophic bacteria can use methane as their only energy and carbon source, and they can be deployed to manufacture a broad range of value-added materials, from single cell protein (SCP) for feed and food applications over biopolymers such as polyhydroxybutyrate (PHB) to value-added building blocks and chemicals. SCP can replace fish meal and soy for fish (aquacultures), chicken and other feed applications, and also become a replacement of meat after suitable treatment, as a sustainable alternative protein. Polyhydroxyalkanoates (PHA) like PHB are a possible alternative to fossil-based thermoplastics. With ongoing and increasing pressure towards decarbonization in many industries, one can assume that natural gas consumption for combustion will decline. Methanotrophic upgrading of natural gas to valuable products is poised to become a very attractive option for owners of natural gas resources, regardless of whether they are connected to the gas grids. If all required protein, (bio)plastics and chemicals were made from natural gas, only 7, 12, 16–32%, and in total only 35–51%, respectively, of the annual production volume would be required. Also, that volume of methane could be sourced from renewable resources. Scalability will be the decisive factor in the circular and biobased economy transition, and it is methanotrophic fermentation that can close that gap

Role of NAD+-Dependent Malate Dehydrogenase in the Metabolism of Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b

We have expressed the l-malate dehydrogenase (MDH) genes from aerobic methanotrophs Methylomicrobium alcaliphilum 20Z and Methylosinus trichosporium OB3b as his-tagged proteins in Escherichia coli. The substrate specificities, enzymatic kinetics and oligomeric states of the MDHs have been characterized. Both MDHs were NAD+-specific and thermostable enzymes not affected by metal ions or various organic metabolites. The MDH from M. alcaliphilum 20Z was a homodimeric (2 × 35 kDa) enzyme displaying nearly equal reductive (malate formation) and oxidative (oxaloacetate formation) activities and higher affinity to malate (Km = 0.11 mM) than to oxaloacetate (Km = 0.34 mM). The MDH from M. trichosporium OB3b was homotetrameric (4 × 35 kDa), two-fold more active in the reaction of oxaloacetate reduction compared to malate oxidation and exhibiting higher affinity to oxaloacetate (Km = 0.059 mM) than to malate (Km = 1.28 mM). The kcat/Km ratios indicated that the enzyme from M. alcaliphilum 20Z had a remarkably high catalytic efficiency for malate oxidation, while the MDH of M. trichosporium OB3b was preferable for oxaloacetate reduction. The metabolic roles of the enzymes in the specific metabolism of the two methanotrophs are discussed

ATP- and Polyphosphate-Dependent Glucokinases from Aerobic Methanotrophs

The genes encoding adenosine triphosphate (ATP)- and polyphosphate (polyP)-dependent glucokinases (Glk) were identified in the aerobic obligate methanotroph Methylomonas sp. 12. The recombinant proteins were obtained by the heterologous expression of the glk genes in Esherichia coli. ATP-Glk behaved as a multimeric protein consisting of di-, tri-, tetra-, penta- and hexamers with a subunit molecular mass of 35.5 kDa. ATP-Glk phosphorylated glucose and glucosamine using ATP (100% activity), uridine triphosphate (UTP) (85%) or guanosine triphosphate (GTP) (71%) as a phosphoryl donor and exhibited the highest activity in the presence of 5 mM Mg2+ at pH 7.5 and 65 °C but was fully inactivated after a short-term incubation at this temperature. According to a gel filtration in the presence of polyP, the polyP-dependent Glk was a dimeric protein (2 × 28 kDa). PolyP-Glk phosphorylated glucose, mannose, 2-deoxy-D-glucose, glucosamine and N-acetylglucosamine using polyP as the phosphoryl donor but not using nucleoside triphosphates. The Km values of ATP-Glk for glucose and ATP were about 78 μM, and the Km values of polyP-Glk for glucose and polyP(n=45) were 450 and 21 μM, respectively. The genomic analysis of methanotrophs showed that ATP-dependent glucokinase is present in all sequenced methanotrophs, with the exception of the genera Methylosinus and Methylocystis, whereas polyP-Glks were found in all species of the genus Methylomonas and in Methylomarinum vadi only. This work presents the first characterization of polyphosphate specific glucokinase in a methanotrophic bacterium