Добірка наукової літератури з теми "Low-grade phosphate"

Experiments were conducted to evaluate the effect of phosphate solubilizing fungi (Aspergillus awamori and Trichoderma viride) in phosphocompost preparation along with low grade rock phosphate. Co-inoculation of phosphate-solubilizing fungi significantly increased the nutrient value of the compost that explores high P-solubilizing potential of A.awamori and T.viride which can be exploited for the solubilization of fixed phosphates thereby enhancing soil fertility and plant growth. Rock phosphate application along with phosphate solubilizing fungi increased 69.2% acid phosphatase and 65% alkaline phosphatase activity over ordinary compost. With co-inoculation, maximum P content (64.3%) was observed followed by single inoculation with A.awamori (62.2%). The present findings revealed that phosphate solubilizing fungi can interact positively in promoting nutrient content of compost and plant growth leading to improved yield.

Low-grade phosphate rock from Sra Ouertane (Tunisia) was beneficiated using a thermal treatment consisting of calcination, quenching, and disliming. Untreated phosphate rock samples (group 1), calcined phosphate rock samples (group 2), as well as calcined, quenched, and dislimed (group 3) phosphate rock samples, were investigated using inductively-coupled plasma atomic emission spectroscopy (ICP-AES), inductively-coupled plasma mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), and X-ray powder diffraction (XRD). Besides, the particle size distribution of the aforementioned three groups was determined. The proposed thermal treatment successfully increased the P2O5 content of the untreated phosphate rock from 20.01 wt% (group 1) to 24.24 wt% (group 2) after calcination and, finally, 27.24 wt% (group 3) after calcination, quenching, and disliming. It was further found that the concentration of relevant accompanying rare earth elements (Ce, La, Nd, Pr, Sm, and Y) was increased and that the concentration of Cd could be significantly reduced from 30 mg/kg to 14 mg/kg with the proposed treatment. The resulting phosphate concentrate showed relatively high concentrations in metal oxides: Ʃ MgO, Fe2O3, Al2O3 = 3.63 wt% and silica (9.81 wt%) so that it did not meet the merchant grade specifications of a minimum P2O5 content of 30 wt% yet. Removal of these elements could be achieved using additional appropriate separation techniques.

A low-grade siliceous sedimentary phosphate rock assaying 22.05% P205 was upgraded by double float (direct and reverse) technology. The rock contains collophane (carbonate fluorapatite) as the valuable phosphate mineral along with siliceous, carbonaceous and clay minerals. A process was developed which yielded a high-grade phosphate concentrate with improved recovery rate. The developed process consists of three parts. The first part includes wet grinding of ore to liberation point followed by separation of fines (slimes) by cone classifier. The finely ground deslimed ore was floated by direct anionic flotation using oleic acid collector to get rougher phosphate concentrate. It was cleaned once using additional quantity of reagents. In the second part, the fines generated during grinding operation were floated by column flotation to recover phosphate values. The cleaned concentrate and column concentrate were mixed together and washed thoroughly with hot water to remove the attached reagents. The final part comprises of cationic flotation of combined phosphate concentrate with fatty amine collector to float away quartz and silicates and to leave behind phosphate values. The grade of final phosphate concentrate was found to be 32.85% P205 with an overall recovery of 88.14%. The concentrate obtained meets the specifications of fertilizer and acid grade.

In view of the mid-low grade phosphate rock somewhere in Yunnan province, first of all study the mechanical properties of ore, on the basis of which combine Duanshi semi diameter theory formula and crushing statistic mechanics, optimized from diameters, shapes and proportion of the grinding medias, increasing the grinding selectivity only to get selective optimization scheme, finally proved by practice, after changing the media system, on the basis of original mill processing capacity increased by 19.54%, the average steel consumption reduced more than 10%, the particle size of grinding product is easy to process, having an obvious energy saving effect.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.01 – технологія неорганічних речовин. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2015. Дисертацію присвячено розробці наукових основ технології комплексних NPCa-добрив з мікроелементами із залученням фосфоровмісної сировини з низьким вмістом фосфору (V) оксиду. Вперше на основі термодинамічних розрахунків, експериментальних досліджень та рентгенофазових аналізів визначено перелік реакцій, що перебігають в процесі взаємодії карбаміду з нітратно-кислотною витяжкою (НКВ). Визначено технологічні параметри взаємодії карбаміду з НКВ та процесу амонізації NPCа-добрив, а також розроблено принципову схему, яка дозволяє отримати низку комплексних NPCa-добрив з мікроелементами по безвідходній технології із залученням фосфоровмісної сировини України з низьким вмістом фосфору (V) оксиду. Встановлено, що взаємодія карбаміду з НКВ відбувається у кінетичній області та створено кінетичну модель процесу, знайдено константи швидкості, енергію активації. Створена математична модель, яка дозволяє розрахувати технологічні параметри процесу і хімічний реактор синтезу. Отримане комплексне NPCa-добриво з мікроелементами завдяки високому вмісту водорозчинної та засвоюваної форм Р₂О₅ та СаО при агрохімічних випробуваннях у Національному науковому центрі "Інститут ґрунтознавства і агрохімії імені О. Н. Соколовського" показало на підвищення врожайності овочевих культур до 12 ÷ 30 %. Доведено їх економічну доцільність.
Dissertation for degree of candidate of technical sciences, specialty 05.17.01 - Technology of inorganic substances. - National Technical University "Kharkov Polytechnic Institute", Kharkov, 2015. Dissertation is devoted to development of scientific bases of technology NPCa - involving phosphorus fertilizer raw materials with low content of phosphorus (V) oxide. For the first time on the basis of thermodynamic calculations and experimental studies, X-ray analysis of a list of reactions in the process of interaction with the urea nitrogen - acid extract (NAE). Defined technological parameters of the interaction of urea with nitrogen - acid extract and ammoniation process NPCa-fertilizers and developed concept that allows you to receive a number of complex NPCa-fertilizer with trace elements of non-waste technology using phosphorus-containing raw materials in Ukraine are low in phosphorus (V) oxide. It was found that the interaction of urea with the nitrogen - acid extract is happening in the kinetic region, established kinetic model of the process, found the rate constants, activation energy. A mathematical model that allows you to calculate the technological parameters of the process and the chemical synthesis reactor. The resulting complex NPCa - fertilizer with trace elements due to the high content of water-soluble and digestible forms of Р₂О₅ and CaO in the agro-chemical tests at the National Scientific Center "Institute for Soil Science and Agricultural Chemistry named after Sokolovsky" has shown an increase in crop yields of up to 12 ÷ 30 %. Prove their economic viability.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.01 – технологія неорганічних речовин. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2015. Дисертацію присвячено розробці наукових основ технології комплексних NPCa-добрив з мікроелементами із залученням фосфоровмісної сировини з низьким вмістом фосфору (V) оксиду. Вперше на основі термодинамічних розрахунків, експериментальних досліджень та рентгенофазових аналізів визначено перелік реакцій, що перебігають в процесі взаємодії карбаміду з нітратно-кислотною витяжкою (НКВ). Визначено технологічні параметри взаємодії карбаміду з НКВ та процесу амонізації NPCа-добрив, а також розроблено принципову схему, яка дозволяє отримати низку комплексних NPCa-добрив з мікроелементами по безвідходній технології із залученням фосфоровмісної сировини України з низьким вмістом фосфору (V) оксиду. Встановлено, що взаємодія карбаміду з НКВ відбувається у кінетичній області та створено кінетичну модель процесу, знайдено константи швидкості, енергію активації. Створена математична модель, яка дозволяє розрахувати технологічні параметри процесу і хімічний реактор синтезу. Отримане комплексне NPCa-добриво з мікроелементами завдяки високому вмісту водорозчинної та засвоюваної форм Р₂О₅ та СаО при агрохімічних випробуваннях у Національному науковому центрі "Інститут ґрунтознавства і агрохімії імені О. Н. Соколовського" показало на підвищення врожайності овочевих культур до 12 ÷ 30 %. Доведено їх економічну доцільність.
Dissertation for degree of candidate of technical sciences, specialty 05.17.01 - Technology of inorganic substances. - National Technical University "Kharkov Polytechnic Institute", Kharkov, 2015. Dissertation is devoted to development of scientific bases of technology NPCa - involving phosphorus fertilizer raw materials with low content of phosphorus (V) oxide. For the first time on the basis of thermodynamic calculations and experimental studies, X-ray analysis of a list of reactions in the process of interaction with the urea nitrogen - acid extract (NAE). Defined technological parameters of the interaction of urea with nitrogen - acid extract and ammoniation process NPCa-fertilizers and developed concept that allows you to receive a number of complex NPCa-fertilizer with trace elements of non-waste technology using phosphorus-containing raw materials in Ukraine are low in phosphorus (V) oxide. It was found that the interaction of urea with the nitrogen - acid extract is happening in the kinetic region, established kinetic model of the process, found the rate constants, activation energy. A mathematical model that allows you to calculate the technological parameters of the process and the chemical synthesis reactor. The resulting complex NPCa - fertilizer with trace elements due to the high content of water-soluble and digestible forms of Р₂О₅ and CaO in the agro-chemical tests at the National Scientific Center "Institute for Soil Science and Agricultural Chemistry named after Sokolovsky" has shown an increase in crop yields of up to 12 ÷ 30 %. Prove their economic viability.

Climate change has become one of the world’s leading threats. Currently, the construction industry has a high environmental footprint. For this reason, the scientific and technological sector is looking for new materials to reduce the environmental consequences of this division. It is well known that the valorisation of different by-products can contribute to the reduction of the energy global consumption and CO2 emissions. Magnesium Phosphate Cement (MPC) can be obtained by using Low Grade Magnesium Oxide (LG-MgO) as a by-product from the industrial process of magnesite calcination. In this research, a Sustainable MPC (Sust-MPC) for different construction purposes is developed by using LG-MgO along with monopotassium phosphate KH2PO4 (MKP) as raw materials. The increasing use of synthetic fibres in clothing, as well as China’s competitive prices on Animal Fibres (AF) market, have led to a commercial interest fibre decrease for wool-like AF in Spain. This study aims to formulate a Sust-MPC cement with Animal Fibre (AF) to reduce the cost of the new material (Sust-MPC-AF) and to increase the thermal insulation, allowing the use of Sust-MPC-AF in several potential applications. Besides, it should be emphasized that the final pH of Sust-MPC is neutral, which allows containing natural fibres. To develop Sust-MPC-AF, some properties such as thermal conductivity, density, Modulus of Elasticity (MoE), flexural strength, and economic cost were evaluated using the Design of Experiments (DoE). The DoE studies allowed obtaining a model for further optimization considering minimum thermal conductivity and cost dosages. The formulation 30L-25EW presents the minimum conductivity (λ=0.140 W·m-1·K-1). Therefore, two optimal dosages (36L-25EW and 24L-22EW) are obtained by considering mixing variables such as AF/Cement ratio (AF/C) and AF/Extra Water ratio (AF/EW).

In recent years, legislative authorities in the US, Europe and Japan have steadily reduced engine exhaust emissions, i.e., carbon monoxide (CO), hydrocarbons (HC), sulphur, particulate matter (PM) and nitrogen oxides (NOx) to improve air quality. To meet these requirements engine manufacturers have had to make significant design changes and as a consequence new engine lubricant specifications from Industry bodies (ACEA, EMA, JAMA) and individual OEMs have had to be introduced to ensure adequate lubrication of these new engines. This has led to significant changes to heavy-duty diesel engine oil (HDDEO) oil formulation composition. Engine design modifications to increase fuel combustion efficiency such as increased peak cylinder pressure and increased fuel injection pressures have placed higher stress on piston rings and liners, bearings and valve train components [1], and improved oil consumption has meant longer oil residence time in the piston ring belt area. The practice of retarded fuel injection timing and exhaust gas recirculation (EGR) as measures to reduce NOx levels by reducing peak combustion temperature has had a considerable impact on lubricant performance. Retarded injection leads to higher soot levels which can cause valve train wear and piston ring liner wear and soot-induced thickening, whilst EGR leads to increased corrosive acids and wear in the combustion chamber. Currently in Europe, Euro 3 heavy-duty engines predominantly use retarded fuel injection as the primary NOx emission control strategy although there are cases where EGR is used. In the US, cooled EGR is used by most engine manufacturers to meet US 2002 emissions. HDDEO’s contain a combination of performance additives such as overbased metal detergents, dispersants, antiwear agents and antioxidants designed to provide wear protection, engine cleanliness, and control of soot contaminants and oxidation. Other additive components include selected viscosity index (VI) improvers and pour point depressants to provide necessary viscosity characteristics and shear stability, and also anti-foam agents for oil aeration control. To meet the increased demands from low emission engines, the chemical composition of the performance additives has been modified and levels increased. Current HDDEOs optimized to meet US and European specifications contain typically between 1.3 and 1.9%wt sulphated ash, 0.1–0.14%wt phosphorus and 0.3–1.1.wt sulphur. To meet the next generation emission standards, engines will require the use of exhaust after-treatment devices. In Europe, Euro 4 emission reductions for NOx and PM, scheduled for introduction in 2005, will require the use of either selective catalytic reduction, or the use of EGR in combination with a diesel particulate filter (DPF). To meet the US 2007 requirements, higher levels of EGR than currently used, in combination with DPFs, is envisaged by most engine builders. Exhaust after-treatment devices are already used extensively in some applications such as DPFs on city buses in Europe and the US. Further NOx restrictions are scheduled for Euro 5 in 2008 and USA in 2010. NOx absorber systems, although used in gasoline engines, are still under development for heavy-duty diesel engines and may be available for 2010. Some lubricant base oil and additive components from oil consumed in the combustion chamber are believed to adversely affect the performance of after-treatment devices. Ash material from metal detergents and zinc dithiophosphates (ZDTP) can build up in the channels within particulate filters causing blockage and potentially loss of engine power, leading to a need for frequent cleaning maintenance. The role of sulphur and phosphorus in additive components is less clear. Sulphur from fuel can either oxidize to sulphur dioxide and react through to sulphuric acid, which manifests itself as particulate, or can have a poisoning effect on the catalyst itself. However, the role of sulphur containing additives is yet to be established. Phosphorus from ZDTP antiwear components can lead to a phosphate layer being deposited on catalyst surfaces, which may impair efficiency. Concerns from OEMs regarding the possible effects of ash, sulphur and phosphorus has led to chemical limits being introduced in some new and upcoming engine oil specifications. The ACEA E6 sequence restricts sulphated ash to 1.0%wt max, phosphorus to 0.08%wt max and sulphur to 0.3%wt max, while the PC-10 category scheduled for 2007 will have maximum limits of 1.0%wt sulphated ash, 0.12%wt phosphorus and 0.4%wt sulphur. The resulting constraints on the use of conventional overbased metal detergent cleanliness additives and zinc dithiophosphate antiwear additives will necessitate alternative engine oil formulation technologies to be developed in order to maintain current performance levels. Indeed, performance requirements of engine oils are expected to become more demanding for the next generation engines where emissions are further restricted. If absorbers become a major route for NOx reduction, limits on sulphur and phosphorus are likely to be more restrictive. Oil formulations meeting ACEA E6 and PC-10 chemical limits have been assessed in several key critical lubricant specification tests, looking at valve train and piston ring/cylinder liner wear, corrosive wear in bearings, piston cleanliness and soot-induced viscosity control. It is demonstrated that it is possible to achieve MB 228.5 extended oil drain performance and API CI-4 wear, corrosion and piston cleanliness requirements for current US engines equipped with EGR [2], at a sulphated ash level of 1.0%wt, and phosphorus and sulphur levels, (0.05 and 0.17%wt, respectively), considerably lower than these chemical limits. This is achievable by the use of selected low sulphur detergents, optimized primary and secondary antioxidant systems and non-phosphorus containing, ashless supplementary antiwear additives blended in synthetic basestocks. Field trials in several city bus fleets have been conducted to assess engine oil performance and durability using one of these low sulphated ash, phosphorus and sulphur (SAPS) oil formulations and to examine lubricant effects on particulate filter performance. Engine oil durability testing was conducted in bus fleets in Germany and Switzerland. These trials, involving over 100 vehicles, cover a range of engine types, e.g., Daimler Chrysler and MAN Euro 1, 2 and 3 and different fuel types (low sulphur diesel, biodiesel, and compressed natural gas) in some MAN engines. The fleets are fitted with continuously regenerating particulate filters either from new or retrofitted. Oils were tested at standard and extended drain intervals (up to 60 000km). Used oil analysis for iron, copper, lead and aluminium with the low SAPS oil in these vehicles have shown low wear rates in all engine types and comparable with a higher 1.8% ash ACEA E4, E5 quality oil. Soot levels can vary considerably, but oil viscosity is maintained within viscosity grade, even at 8% soot loading. TBN depletion and TAN accumulation rates are low showing significant residual basicity reserve and control of acidic combustion and oxidation products. Buses in Stuttgart and Berlin have been used to investigate lubricant ash effects of engine oil on particulate filter durability. Exhaust back-pressure is routinely measured and DPF filters removed and cleaned when back pressure exceeds 100 mbar. Comparison of rate of back pressure build up as a function of vehicle distance shows reduced back pressure gradients for the low SAPS oil relative to the 1.8%wt ash oil in both engine types looked at. An average reduction in back pressure gradient of 40% was found in buses equipped with OM 906LA engines in Berlin and 25% with OM 457hLA engines at both locations. Examination of the ash content in DPFs has shown a 40% reduction in the quantity of ash with the low SAPS oil. This investigation shows that it is possible to meet current long oil drain requirements whilst meeting chemical limits for future lubricants and provide benefits in DPF durability.