Challenges and opportunities for energy recovery from municipal solid waste in the Russian Federation

Energy recovery from municipal solid waste (MSW) is currently a key factor in waste management in Russia, as can be seen from the corresponding changes in the state regulatory framework. The paper presents a comparative assessment of different waste flow characteristics; it focuses on pre-treatment options and the method of subsequent thermal treatment. It reflects the basic method of untreated MSW incineration and other advanced technologies which have different levels of waste preparation. Step-by-step research has been carried out in a large Russian city in order to determine different technological approaches to recovering energy from MSW. The study included: 1) field studies of the composition and characterization of MSW; 2) laboratory studies of MSW thermal properties, i.e. moisture, ash content and calorific value; 3) several options for waste treatment schemes with equipment of different technical specifications; 4) analysis of material flow, energy flow and key substance flow according to these considered schemes. The research revealed that for all seasons a significant proportion of MSW (almost 40%) is represented by fines (below 50 mm). On average, the energy potential of MSW (the total content of waste paper, polymers, textiles, wood, multilayer packaging, leather, rubber, footwear) amounts to about 40%. It was found that MSW calorific value depends on fraction size, since screening (over 50 mm) is characterized by high moisture and low content of valuable components, compared to MSW greater than 50 mm in size. Pre-processing and treatment of MSW allows solid recovered fuel (SRF) to be obtained with a calorific value similar to brown coal. The energy balance of the process allows the conclusion that 33.8% of initial MSW energy potential is concentrated in residues from the sorting process, since it has a relatively low calorific value of 4.8 MJ/kg, but a high mass fraction of 47.9%. In the process of MSW treatment and solid fuel production, most of the chlorine and mercury (80% and 55% respectively) is removed by the rest of the sorting process. The data obtained in the study can be used in selecting the optimal option for energy recovery from MSW. © 2019 WIT PressACKNOWLEDGEMENT The work was supported by Act 211 Government of the Russian Federation, contract № 02.A 03.21.0006

Transport in the static diffusion cloud chamber revisited

The static diffusion chamber (SDC) allows the measurement of critical supersaturation and of nucleation rates and it is a powerful instrument for the vapor nucleation study. Earlier, within the scope of the International Nucleation Workshop Group, nucleation rates of the n-pentanol–helium system have been measured using different experimental techniques. Disagreement of experimental data obtained using the static diffusion chamber and data obtained using other methods, particularly the laminar flow diffusion chamber, can be explained by re-examining the mass and energy transport analysis used to describe static diffusion chamber operation. In the present research we describe the mass and energy transport in the SDC modeled as an effectively open system with mass and energy transport in one direction with a nonzero diffusion flux at the system boundaries. Calculated values for vapor supersaturation are compared with the n-pentanol nucleation rate experimental results of the American–Czech group [M. Rudek, J. L. Katz, I. Y. Vidensky et al., J. Chem. Phys. 111, 3623 (1999)] and with a nucleation rate Reference Equation obtained from an earlier investigation involving the n-pentanol–helium system. From our results one can see that there is a significant difference in the calculated supersaturation for all of the data. The magnitude of this difference is quite large even for the relatively small vapor mass fractions at a nucleation temperature of 260 K. We also note that the calculated nucleation temperatures from our analysis are slightly larger than those reported in the work of Rudek et al.4 We performed our calculations with and without the thermal diffusion term. We observed that the effect of thermal diffusion on the transport process is relativelly small and is not particularly essential to include in this comparison that we are making the effects of the different flux boundary conditions

Research of Possibility of Processing of Oxidized Nickel Ore by Chloride Sublimation Roasting Technology

Oxidized nickel ores (ONO) contain most of the world's nickel reserves. However, choice of a cost-effe nickel ore processing technology is difficult due to the dispersed distribution of nickel compounds in refractory minerals, low nickel content, presence of a large amounts of consuming host rocks, and impossibility of beneficiation by conventional physicochemical methods. The paper presents studies on the ONO processing technology by means of chloride sublimation roasting. Sodium and calcium chlorides were used as chlorinating agents both individually and in various ratios. It has been shown that roasting allows for nickel and cobalt conversion into chloride form followed by selective distillation of the resulting compounds into the gas phase by 89 - 90% at a roasting temperature of 1100 C. © Published under licence by IOP Publishing Ltd

Research of the Technology of Joint Processing of Stale Copper-Smelting Slags and Pyrite Cinders with the Extraction of Non-Ferrous Metals into a Commercial Product

The article deals with the problems of slags processing from copper-smelting production, both current production and those which had been accumulating over many years of enterprises' activity in heaps (stale). There are data about possible methods of slag processing. It is proposed a technology for the joint processing of stale copper-smelting slags of the Urals and pyrite cinders (waste from the production of sulfuric acid) - smelting with obtain a poor matte, into which copper and precious metals will be transferred. The results of scientific research on matte melting are presented. It is shown that when the ratio in the furnace charge "stale slag: pyrite cinder"at the level of 2.5, the extraction of non-ferrous metals into the matte is at the level of 90%. © Published under licence by IOP Publishing Ltd

Nickel sorption from solutions with high salt concentration

The object of the study is salt concentrates formed as a result of treatment of concentrated acidic and alkaline wastewater of galvanic processes, realized on Ural Optical & Mechanical Plant (Russia). Salt concentrates are to be disposed of as low-hazard substances, but periodically the presence of nickel ions in them was detected. Concentration of nickel ions reaches up to 0.3 g/L, the total salt content reaches 200 g/L. The possibility of sorption purification of salt concentrates from nickel on the aminocarboxylicionite Lewatit TP 207 was studied, and the capacitance characteristics of the ionite were determined. It is shown that a high salt background does not reduce the ion exchange capacity of ionite for nickel. The dynamic capacity of Lewatit TP 207 before the breakthrough was 0.155 g/g. Nickel desorption is carried out with 20% sulfuric acid. The maximum concentration of nickel in the eluates was 25.484 g/L. Such eluates can be returned to the nickel-plating bath. The technology of periodic ion-exchange purification of salt concentrates is proposed. © Published under licence by IOP Publishing Ltd

To the Problem of Reducing the Amount of Harmful Emissions when Refining Silver

The work is devoted to the study of the possibilities of minimizing the release of nitrogen oxides during the dissolution of silver in nitric acid solutions during refining of the gold and silver alloy. Using a rotating disk, the maximum concentration of nitric acid is determined, at which the oxidation potential of the system is insufficient for the oxidation of silver. It has been established that at a temperature of 363 K and a concentration of HNO3 = 50 g/dm3, the dissolution rate of silver does not exceed 0,00022∙10-5 mol/(cm2 ∙ s) and such conditions can be considered as background for an environmentally friendly process. To initiate dissolution, hydrogen peroxide was used as an alternative oxidizing agent. As a criterion for the rational use of the oxidant and the ecological purity of the process, the excess pressure over the solution was evaluated. The influence of the initial and current composition of the solution, temperature, and conditions of oxidant supply to the reactor on the kinetics of the target process was studied. It is shown that at a silver dissolution rate of 2,7∙10-6 mol/(cm2 ∙ s), no release of nitrogen oxides was observed.Работа посвящена исследованию возможностей минимизации выделения оксидов азота при растворении серебра в азотнокислых растворах при рафинировании сплава золота и серебра. С использованием вращающегося диска определена максимальная концентрация азотной кислоты, при которой окислительный потенциал системы недостаточен для окисления серебра. Установлено, что при температуре 363 K и концентрации HNO3 = 50 г/дм3 скорость растворения серебра не превышает 0.00022∙10-5 моль/(см2 с) и такие условия могут быть рассмотрены как фоновые для экологически чистого процесса. Для инициирования растворения в качестве альтернативного окислителя использовали пероксид водорода. В качестве критерия рационального использования окислителя и экологической чистоты процесса оценивали избыточное давление над раствором. Изучены влияние начального и текущего состава раствора, температуры, условий подачи окислителя в реактор на кинетику целевого процесса. Показано, что при скорость растворения серебра 2,7∙10-6 моль/(см2 с) выделение оксидов азота не наблюдалось

Двухстадийное солянокислое выщелачивание окисленной никелевой руды Серовского месторождения

Significant reserves of oxidized nickel ores are concentrated in the Ural region, in the deposits of various sizes that are mined by open-pit method. Ore is rather loose, which makes the cost of production relatively low. At the same time, the technologies employed at Ural nickel plants fail to meet the energy conservation requirements, and they are environmentally unfriendly and unprofitable. The paper proposes a two-stage hydrometallurgical technology for processing oxidized nickel ores from the Serovsky deposit. The composition of investigated ore is, wt.%: 1.01 Ni, 0.031 Co, 15.32 Fetotal, 8.51 Al2O3, 21.76 MgO, 43.97 SiO2. The phase composition of the sample was determined by powder diffraction on the XRD-7000 X-ray diffractometer (Shimadzu, Japan). Serpentine Mg6[Ni, Si4O10](OH)8 and nimite (Ni, Mg, Al)6(Si, Al)4О10(OH)8 were identified as the main nickel-containing minerals. Nickel enters the crystal lattice of silicates and replaces magnesium and iron isomorphically, which significantly complicates the disintegration of such minerals by the hydrometallurgical method. The paper provides the results of laboratory studies into atmospheric ore leaching with hydrochloric acid at the first stage and autoclave leaching of the obtained slurry at the second stage depending on temperature, leaching time and acid consumption. The total (in two stages) extraction into the solution was, wt.%: 82 Ni, 73.6 Co, 22 Fe, 22 Mg, 50.4 Al. Hydrochloric acid is almost completely consumed under these conditions with residual acid concentration of about 3 g/dm3. The autoclave slurry has good filterability. Cake composition after autoclave leaching is as follows, wt.%: 0.35 Ni, 0.01 Co, 12 Fetotal, 10.63 Mg, 1.2 Al, 55 SiO2.В Уральском регионе сосредоточены значительные запасы окисленных никелевых руд как в крупных, так и в небольших месторождениях, которые разрабатываются открытым способом. Руда достаточно рыхлая, что делает стоимость добычи относительно невысокой. В то же время технологии, используемые на уральских никелевых заводах, не удовлетворяют требованиям энергосбережения и экологии и являются убыточными. В работе предложена двухстадийная гидрометаллургическая технология переработки окисленных никелевых руд Серовского месторождения. Исследована руда следующего состава, мас.%: 1,01 Ni, 0,031 Co, 15,32 Feобщ, 8,51 Al2O3, 21,76 MgO, 43,97 SiO2. Фазовый состав пробы установлен методом порошковой дифракции на рентгеновском дифрактометре XRD-7000 («Shimadzu», Япония). Основными никельсодержащими минералами идентифицированы серпентин Mg6[Ni, Si4O10](OH)8 и нимит (Ni, Mg, Al)6(Si, Al)4О10(OH)8. Никель входит в кристаллическую решетку силикатов, изоморфно замещая магний и железо, что существенно затрудняет вскрытие таких минералов гидрометаллургическим способом. Приведены результаты лабораторных исследований атмосферного выщелачивания руды соляной кислотой (на первой стадии) и автоклавного выщелачивания полученной пульпы (на второй) в зависимости от температуры, продолжительности выщелачивания и расхода кислоты. Суммарное (по двум стадиям) извлечение в раствор составило, мас.%: 82 Ni, 73,6 Co, 22 Fe, 22 Mg, 50,4 Al. Соляная кислота в данных условиях расходуется практически полностью – ее остаточная концентрация составила около 3 г/дм3 . Автоклавная пульпа обладает хорошей фильтруемостью. Состав кека после автоклавного выщелачивания, следующий, мас.%: 0,35 Ni, 0,01 Co, 12 Feобщ, 10,63 Mg, 1,2 Al, 55 SiО2