Iron removal stations’ sludges postprocessing for its resource potential identification

Introduction. The sludge of the washing waters of the underground water iron removal station is a large-tonnage technogenic waste that is dangerous for the environment. The homogeneous chemical composition and finely dispersed structure of the sludge make it possible to consider it as a valuable raw material for the production of various products in the conditions of a forward movement towards a circular economy. Obtaining nanosized metal powders from the sludge of iron removal stations has a number of advantages over traditional physical, chemical and mechanical methods. To optimize the process of obtaining highly dispersed metal powders from the sludge of iron removal stations, it is necessary to study the influence of the main technological parameters on the size, shape and chemical composition of the final material. Materials and methods. Thermal treatment of the sludge of the iron removal station in the carbon monoxide medium was carried out in the temperature range of 400–600 °C. Ultrasonic dispersion was used to get an idea of the true particle size. The granulometric composition of the sludge was studied by electron microscopy and laser beam scattering. Results. The results of experimental studies of the granulometric composition of the treated sludge of iron removal stations are presented. The particles obtained at a temperature of 450 °C had the most pronounced spherical shape, low open porosity, and a low degree of adhesion to neighboring particles. These properties are key for micro- and nanopowder-based products. An increase in the temperature of sludge processing led to the adhesion of particles and their fusion into large aggregates with a brittle structure as a result of the development of crystallization processes. Conclusions. The proposed methods of physicochemical treatment in an environment of carbon monoxide and ultrasonic action of the sludge of an iron removal station, which is currently a technogenic waste, makes it possible to obtain a highly dispersed metal powder. This material has the necessary properties for use in modern high-tech industries.

Download Full-text

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping

Sensors ◽

10.3390/s21134425 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4425

Author(s):

Ana María Pineda-Reyes ◽

María R. Herrera-Rivera ◽

Hugo Rojas-Chávez ◽

Heriberto Cruz-Martínez ◽

Dora I. Medina

Keyword(s):

Carbon Monoxide ◽

High Performance ◽

Gas Sensing ◽

Experimental Studies ◽

Electrical Performance ◽

Long Term Stability ◽

Sensing Applications ◽

Recent Advances ◽

Sensitivity And Selectivity ◽

Doped Zno

Monitoring and detecting carbon monoxide (CO) are critical because this gas is toxic and harmful to the ecosystem. In this respect, designing high-performance gas sensors for CO detection is necessary. Zinc oxide-based materials are promising for use as CO sensors, owing to their good sensing response, electrical performance, cost-effectiveness, long-term stability, low power consumption, ease of manufacturing, chemical stability, and non-toxicity. Nevertheless, further progress in gas sensing requires improving the selectivity and sensitivity, and lowering the operating temperature. Recently, different strategies have been implemented to improve the sensitivity and selectivity of ZnO to CO, highlighting the doping of ZnO. Many studies concluded that doped ZnO demonstrates better sensing properties than those of undoped ZnO in detecting CO. Therefore, in this review, we analyze and discuss, in detail, the recent advances in doped ZnO for CO sensing applications. First, experimental studies on ZnO doped with transition metals, boron group elements, and alkaline earth metals as CO sensors are comprehensively reviewed. We then focused on analyzing theoretical and combined experimental–theoretical studies. Finally, we present the conclusions and some perspectives for future investigations in the context of advancements in CO sensing using doped ZnO, which include room-temperature gas sensing.

Download Full-text

Controlled atmosphere GMAW welding of transportation vehicles and production machines parts made from 30MnB5 steel

MATEC Web of Conferences ◽

10.1051/matecconf/201821603001 ◽

2018 ◽

Vol 216 ◽

pp. 03001 ◽

Cited By ~ 1

Author(s):

Evgeny Ivanayskiy ◽

Aleksei Ishkov ◽

Aleksandr Ivanayskiy ◽

Iakov Ochakovskii

Keyword(s):

Mechanical Properties ◽

Carbon Dioxide ◽

Carbon Monoxide ◽

Chemical Composition ◽

Controlled Atmosphere ◽

Shielding Gas ◽

Reducing Atmosphere ◽

Metal Composition ◽

Gmaw Welding ◽

Welding Materials

The paper studies the influence of shielding gas on the composition and the structure of weld joint metal of 30MnB5 steel applied in essential parts of automobiles and tractors. The welding was performed in inert, oxidizing and reducing atmospheres. It was established that TIG welding with argon used as shielding gas did not provide the required mechanical properties when using conventional welding materials. Carbon dioxide during MAG welding caused partial burning of alloying elements. Carbon monoxide used as shielding gas was proved to form reducing atmosphere enabling to obtain chemical composition close to the base metal composition. Metallographic examinations were carried out. The obtained results provided full-strength weld, as well as the required reliability and durability of welded components and joints.

Download Full-text

The study on decreasing of nitrogen oxides emission carried out on DKVR 10-13 industrial heating boilers

E3S Web of Conferences ◽

10.1051/e3sconf/20184400056 ◽

2018 ◽

Vol 44 ◽

pp. 00056 ◽

Cited By ~ 1

Author(s):

Sylwia Janta-Lipińska ◽

Alexander Shkarovskiy

Keyword(s):

Carbon Monoxide ◽

Nitrogen Oxides ◽

Experimental Studies ◽

Steam Injection ◽

Reference Level ◽

Optimal Parameters ◽

End Caps ◽

Atmosphere Pollution ◽

Industrial Heating ◽

Study Plan

Nitrogen oxides are considered to be much more toxic than, for example, carbon monoxide. For this reason, the Authors developed and implemented a method for decrease of NOX emission into the atmosphere from DKVR 10-13 boilers. As an effective method for boilers propose injection of steam into the combustion zone. After series of experimental studies an optimal design of the head for steam injection was developed, according to the proprietary technology. The injector head was kept unchanged while the spraying end caps were modified (Fig. 2). Three levels of possible impact of emissions from boiler on the atmosphere pollution were taken into account during studies. After the analysis, it was assumed that the level of the real maximum emission should be taken as the reference level in relation to which the decrease of NOX emission should be determined. The results obtained by the Authors calculated into mass emission and as objective values of nitrogen oxides concentration calculated into α = 1 (Figures 3 and 4). Realization of the study plan, assumed by the Authors, allowed to determine the optimal parameters of the NOx emission decrease method, assuming the expected 30% level of emission decrease at a limited consumption of injected.

Download Full-text

Analysis of the treatment of plastic from electrical and electronic waste in the Republic of Serbia and the testing of the recycling potential of non-metallic fractions of printed circuit boards

Hemijska industrija ◽

10.2298/hemind160415037v ◽

2017 ◽

Vol 71 (3) ◽

pp. 271-279

Author(s):

Aleksandra Vucinic ◽

Zeljko Kamberovic ◽

Milisav Ranitovic ◽

Tihomir Kovacevic ◽

Irena Najcevic

Keyword(s):

Chemical Composition ◽

Printed Circuit Boards ◽

Electronic Waste ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards ◽

Mechanical Methods ◽

The Republic ◽

Electrical And Electronic Waste ◽

Metallic Fractions

This paper presents the analysis of the quantity of plastic and waste printed circuit boards obtained after the mechanical treatment of electrical and electronic waste (E-waste) in the Republic of Serbia, as well as the recycling of non-metallic fractions of waste printed circuit boards. The aim is to analyze the obtained recycled material and recommendation for possible application of recyclables. The data on the quantities and treatment of plastics and printed circuit boards obtained after the mechanical treatment of WEEE, were gained through questionnaires sent to the operators who treat this type of waste. The results of the questionnaire analysis showed that in 2014 the dismantling of E-waste isolated 1,870.95 t of plastic and 499.85 t of printed circuit boards. In the Republic of Serbia, E-waste recycling is performed exclusively by using mechanical methods. Mechanical methods consist of primary crushing and separation of the materials which have a utility value as secondary raw materials, from the components and materials that have hazardous properties. Respect to that, the recycling of printed circuit boards using some of the metallurgical processes with the aim of extracting copper, precious metals and non-metallic fraction is completely absent, and the circuit boards are exported as a whole. Given the number of printed circuit boards obtained by E-waste dismantling, and the fact that from an economic point of view, hydrometallurgical methods are very suitable technological solutions in the case of a smaller capacity, there is a possibility for establishing the facilities in the Republic of Serbia for the hydrometallurgical treatment that could be used for metals extraction, and non-metallic fractions, which also have their own value. Printed circuit boards granulate obtained after the mechanical pretreatment and the selective removal of metals by hydrometallurgical processes was used for the testing of the recycling potential. Granulometric analysis as well analysis of chemical composition of obtained fractions was performed. Subsequently, the manual classification of different types of polymeric material contained in the granulate was made, and both the apparent specific gravity and the chemical composition of the classified types of polymeric materials were determined. Chemical composition of granulate was determined by X-Ray Fluorescence (XRF) using Thermo Scientific Niton XL 3t, while the identification of residual polymers was determined by the FTIR (Fourier Transform Infrared Spectroscopy) method on the Bomen MB 100 device in range 4000 to 400 cm?1. Based on the results of this study, it can be concluded that after the hydrometallurgical treatment of printed circuit boards, and the separation of metals that have the highest value, the residual non-metallic fraction have the utility value and can be used for various purposes, such as developing new polymer materials for technical purposes that have been investigated by many researchers and mentioned in this article.

Download Full-text

Oscillations, glow and ignition in carbon monoxide oxidation in an open system. I. Experimental studies of the ignition diagram and the effects of added hydrogen

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1985.0002 ◽

1985 ◽

Vol 397 (1812) ◽

pp. 21-44 ◽

Cited By ~ 36

Keyword(s):

Carbon Monoxide ◽

Open System ◽

Reaction Rate ◽

Experimental Studies ◽

Reaction Rates ◽

Step Change ◽

Stable Node ◽

Stationary States ◽

Show Evidence ◽

Oxidation Of Carbon Monoxide

The oxidation of carbon monoxide in equimolar mixtures (CO + O 2 ) has been studied in a well-stirred open system (0.5 dm 3 ) at vessel temperatures in the range 700-840 K, and reactant pressures up to 100 Torr ( ca . 13.3 kPa) at a mean residence time of 8.5 s. Stationary states are established and oscillatory states sustained indefinitely in this system. The effect of small quantities of added hydrogen is studied by a carefully controlled, continuous supplement to the principal reactants. Four different modes of reaction (I-IV) have been characterized, and conditions for their occurrence mapped on a reactant pressure-vessel temperature ( p - T a ) ignition diagram. Most boundaries are quite sharp, and some show evidence of hysteresis. Close to the axes, reaction is slow, non-luminous and non-oscillatory (I). Within a first broad promontory (II) reaction is accompanied by steady luminescence. Crossing the boundary is not accompanied by a step change in reaction rate, but there is a change in character from stable node (in I) to stable focus (in II). Auto-oscillatory luminescence occurs in a closed region (III) wholly within the promontory II. The effects of adding hydrogen on all these modes is to increase the reaction rates markedly and to make them non-isothermal; the boundaries between I, II and III are not as greatly affected. However, systems to which more than 0.10% H 2 have been added also display a new mode, of oscillatory ignition. This appears at first in a region (IV) of high temperatures and pressures but as more H 2 is increased its realm expands and it eventually dominates the ignition diagram, invading the region of luminescence and soon obliterating the oscillatory part completely.

Download Full-text

Influence of different temperature regimes at torrefaction of chicken litter on yield and properties of products

E3S Web of Conferences ◽

10.1051/e3sconf/201911406007 ◽

2019 ◽

Vol 114 ◽

pp. 06007

Author(s):

Olga Larina ◽

Yana Pudova

Keyword(s):

Chemical Composition ◽

Thermogravimetric Analysis ◽

Liquid Fraction ◽

Experimental Studies ◽

Calorific Value ◽

Solid Residue ◽

Optimum Temperature ◽

Volume Yield ◽

Temperature Regimes ◽

Chicken Litter

The purpose of the research is study the influence of the torrefaction process on the fuel properties of the chicken litter. Experimental studies on lab-scale system at five temperature regimes of torrefaction (220, 240, 260, 280, and 300 °C) with a holding time determined using thermogravimetric analysis were conducted. The products of the torrefaction are solid residue, non-condensable gases, and tar. For the feedstock and torrefied material the elemental composition, the lower calorific value, hygroscopicity limit and bulk density are determined. For liquid fraction the analysis of the chemical composition is carried out. The properties of non-condensable gases as chemical composition and calorific value - are investigated. Mass yields of the solid residue and tar, and specific volume yield of the non-condensable gases are presented. The conclusion about the optimum temperature regime for torrefaction of chicken litter based on the results of experimental studies is made.

Download Full-text