Study and development of hardening mixture composition based on unconventional industrial waste

Relevance. Phosphogypsum, the product of apatites chemical processing, is one of the most common mining wastes. Phosphogypsum utilization is not widespread yet, therefore its cost is low. Integrated research has been carried out to determine the technological capacity and economic feasibility of phosphogypsum, sludge, and dolomite utilization as binders in the conversion of ore production techniques. Research aim is to develop a hardening mixture composition based on unconventional industrial waste, determine the technological capacity and economic feasibility of utilizing phosphogypsum, sludge, dolomite, and other accessible low activity wastes as a substitute for expensive and relatively scarce binder material. Research methodology. Initial data are studied of the wastes possessing binding properties. The efficiency of admixing them is determined from the robustness of hardening backfill mixtures control samples that have been produced in laboratory conditions. Based on the research, a database is created to apply the results in practice for mining development. Results. The hardening materials compositions were obtained based on unconventional industrial waste including hydrometallurgical and dressing tailings, furnace clinker, low-grade sand, thermal power plants (TPP) and chemical industry ashes. The optimal composition of the mixture per cubic meter: tailings – 600–750 kg; TPP ash – 180–220 kg; cement dust – 250–315 kg; cement – 35–40 kg; tempering water – 450–515 l under the mixture’s fluidity of about 14 cm according to the readings of the mortar consistency measuring device (StroyTsNIL cone). To ensure radiation safety of the hardening mixture that is based on unconventional industrial waste, it is advisable to take into account not only their chemical and physical-mechanical indicators but the value of naturally radioactive nuclides’ effective activity as well. Conclusions. It has been stated that the robustness of mixtures containing gypsum is 1.5–2.0 times higher, and under the hardening time of 3, 6 and 12 months makes up 3.1; 5.7 and 7.6 MPa correspondingly. It has been shown that the compositions with the binder’s flow rate of 450 kg per cubic meter under the cement : sludge ratio of 1 : 2 show the robustness from 2.8 to 4.9 MPa in 28 days. The content of low-grade sand levigate particles reaches 20% and more. Classes with a specific area of 28.4 m2/kg refer to fine sand, and with a specific area of 27.7 m2/kg refer to medium sand. The robustness of the 28 days old composition reaches 0.5 MPa, 90 days – 0.9 MPa depending on the cement flow rate. It has been substantiated that binders based on fluorine gypsum, phosphogypsum, and belite sludge by mixed grinding of the granulated 26 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 3. 2021 ISSN 0536-1028 blast-furnace slug with the ferrochrome sludge and phosphogypsum up to 70%, 0.08 mm size, show the robustness of the binder up to 3.0 MPa with the flow rate of 450 kg per a cubic meter of the mixture. Keywords: industrial waste; hardening mixture; binder; PPT ash; ash and slag; cement; fluorine gypsum; phosphogypsum; non-reactive aggregate; belite sludge; naturally radioactive nuclides. Acknowledgements. Specialists from Platov South-Russian State Polytechnic University (Novocherkassk, Russia), Ukrainian Research and Design Institute of Industrial Technology (Zhovti Vody, Ukraine), Vostochnyy (Eastern) Mining and Enrichment Combine (Zhovti Vody, Ukraine), Dnipro University of Technology (Dnipro, Ukraine) and others took part in creating, improving, and introducing R&D.

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Understanding the Effect of Stepwise Irrigation on Liquid Holdup and Hysteresis Behavior of Unsaturated Ore Heap

Minerals ◽

10.3390/min11111180 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1180

Author(s):

Leiming Wang ◽

Shenghua Yin ◽

Bona Deng

Keyword(s):

Flow Rate ◽

Packed Bed ◽

Critical Issue ◽

Low Grade ◽

Residual Liquid ◽

Liquid Holdup ◽

Measuring Device ◽

Hysteresis Behavior ◽

Liquid Retention ◽

Relative Porosity

Liquid is a crucial medium to contain soluble oxygen, valuable metal ions, and bacteria in unsaturated heap leaching. Liquid retention behavior is the first critical issue to be considered to efficiently extract low-grade minerals or wastes. In this study, the residual liquid holdup of an unsaturated packed bed was quantitatively discussed by liquid holdup (θ), residual liquid holdup (θresidual), relative liquid holdup (θ’), and relative porosity (n*) using the designed measuring device. The detailed liquid holdup and the hysteresis behavior under stepwise irrigation are indicated and discussed herein. The results show that relative porosity of the packed bed was negatively related to particle size, and intra-particle porosity was more developed in the −4.0 + 2.0 mm packed bed. The higher liquid retention of the unsaturated packed bed could be obtained by using stepwise irrigation (incrementally improved from 0.001 to 0.1 mm/s) instead of uniform irrigation (0.1 mm/s). It could be explained in that some of the immobile liquid could not flow out of the unsaturated packed bed, and this historical irrigation could have accelerated formation of flow paths. The θ was sensitive to superficial flow rate (or irrigation rate) in that it obviously increased if a higher superficial flow rate (u) was introduced, however, the θresidual was commonly affected by n* and θ’. Moreover, the liquid hysteresis easily performed under stepwise irrigation condition, where θ and θresidual were larger at u of the decreasing flow rate stage (DFRS) instead of u of the increasing flow rate stage (IFRS). These findings effectively quantify the liquid retention and the hysteresis behavior of ore heap, and the stepwise irrigation provides potential possibility to adjust liquid retention conditions.

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Cost–Benefit Analysis of Municipal Sludge as a Low-Grade Nutrient Source: A Case Study from South Africa

Sustainability ◽

10.3390/su12239950 ◽

2020 ◽

Vol 12 (23) ◽

pp. 9950

Author(s):

Eyob Habte Tesfamariam ◽

Zekarias Mihreteab Ogbazghi ◽

John George Annandale ◽

Yemane Gebrehiwot

Keyword(s):

Cost Benefit Analysis ◽

Arid Zone ◽

Economic Value ◽

Cost Benefit ◽

Economic Feasibility ◽

Inorganic Fertilizer ◽

Bench Mark ◽

Low Grade ◽

Municipal Sludge ◽

Humid Zone

Municipal sludge has economic value as a low-grade fertilizer as it consists of appreciable amounts of the macro and micronutrients. When using sludge as fertilizer, the economic aspect should be taken into account. In this study, the following specific objectives were identified: (a) to investigate the economic feasibility of using sludge as a fertilizer; (b) to estimate the maximum economic distance sludge can be transported as a fertilizer; and (c) to test the economic feasibility of selling sludge using commercial inorganic fertilizer as a bench mark. The study showed that for anaerobically digested, paddy dried, municipal sludge consisting of 3% N, 2% P, and 0.3% K the economic feasibility of transporting the sludge was limited to a diameter of 20 km in the arid zone, 28 km in the semi-arid zone, 51 km in the sub humid zone, 66 km in the humid zone, and 75 km in the super-humid zone. Therefore, the economic feasibility of using sludge as a substitute for or complementary to commercial inorganic fertilizer is dictated by the distance between the wastewater care work and the farm, sludge nutrient concentration, agro-ecological zone (rain and temperature), and the real-time commercial inorganic fertilizer price.

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Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

Green Processing and Synthesis ◽

10.1515/gps-2021-0008 ◽

2021 ◽

Vol 10 (1) ◽

pp. 157-168

Author(s):

Biwei Luo ◽

Pengfei Li ◽

Yan Li ◽

Jun Ji ◽

Dongsheng He ◽

...

Keyword(s):

Particle Size ◽

Fly Ash ◽

Reaction Time ◽

Carbothermal Reduction ◽

Industrial Waste ◽

Phosphate Rock ◽

Molar Ratio ◽

Low Grade ◽

Carbon Excess ◽

Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

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Empirical Model to Estimate Mn2+ Precipitation Rate from a Leaching Solution Using SO2/O2 as Oxidizing Agent

MRS Proceedings ◽

10.1557/opl.2012.407 ◽

2012 ◽

Vol 1380 ◽

Author(s):

S. Bello-Teodoro ◽

R. Pérez-Garibay

Keyword(s):

Flow Rate ◽

Gas Flow ◽

Reaction Rates ◽

Precipitation Process ◽

Low Grade ◽

Gas Flow Rate ◽

Oxidative Precipitation ◽

Leaching Solution ◽

Good Concordance ◽

Main Influence

ABSTRACTA method, based in leaching with SO2, to process low grade pyrolusite minerals has shown good results at laboratory scale. After the separation of the solid impurities, the dissolved manganese is subsequently precipitated using the SO2/O2 gas mixture as oxidising agent. In this research it was obtained a mathematical model to estimate the oxidative precipitation process, as a function of temperature, pH and SO2 gas flow rate. It was found that pH and temperature have the main influence in the reaction rate. An optimal SO2 concentration in the mixture must be used to avoid generation of reductive conditions. It was observed a most efficient reaction with a low gas flow rate injection. The predicted reaction rates presents a good concordance with the experimental results (R2=0.97), showing a worthy potential for practical uses.

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Operation performance study and numerical analysis of the multi-objective adsorption system driven by low-grade heat of solar energy and industrial waste heat

Solar Energy ◽

10.1016/j.solener.2020.02.060 ◽

2020 ◽

Vol 199 ◽

pp. 575-584

Author(s):

Zisheng Lu

Keyword(s):

Numerical Analysis ◽

Solar Energy ◽

Industrial Waste ◽

Waste Heat ◽

Low Grade ◽

Adsorption System ◽

Performance Study ◽

Operation Performance ◽

Industrial Waste Heat ◽

Low Grade Heat

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Feasibility limits of using low-grade industrial waste heat in symbiotic district heating and cooling networks

Clean Technologies and Environmental Policy ◽

10.1007/s10098-020-01875-2 ◽

2020 ◽

Vol 22 (6) ◽

pp. 1339-1357 ◽

Cited By ~ 1

Author(s):

Maurizio Santin ◽

Damiana Chinese ◽

Alessandra De Angelis ◽

Markus Biberacher

Keyword(s):

Industrial Waste ◽

Waste Heat ◽

District Heating ◽

Low Grade ◽

Heating And Cooling ◽

Industrial Waste Heat

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Overview of the Development and Application of the Twin Screw Expander

Energies ◽

10.3390/en13246586 ◽

2020 ◽

Vol 13 (24) ◽

pp. 6586

Author(s):

Junying Wei ◽

Qi Hua ◽

Jidai Wang ◽

Zheng Jiang ◽

Jihong Wang ◽

...

Keyword(s):

Energy Consumption ◽

Industrial Waste ◽

Waste Heat ◽

Utilization Rate ◽

Low Grade ◽

Total Energy Consumption ◽

The Sustainable Development ◽

Industrial Energy ◽

Industrial Waste Heat ◽

Current Utilization

With the development of society, the energy crisis has become increasingly prominent, which greatly affects the sustainable development of the economy of various countries. Industrial energy consumption accounts for more than 70% of China’s total energy consumption, of which more than 50% is converted to industrial waste heat, and recyclable waste heat resources account for about 60% of the total waste heat resources, while China’s current utilization rate of industrial waste heat only reaches about 30%. The development of renewable energy and recovery of low-grade waste heat in industry is the key to solve the problem. As a type of volumetric expander with full flow expansion, the screw expander is extensively applied in the industrial waste heat recovery and geothermal energy generation industry because of its effective utilization of low enthalpy energy. Improving the performance of the screw expander as the core, the paper concludes and summarizes the research status of the leakage, rotor geometry, sealing and lubrication, processing and manufacturing, which can affect the performance of the screw expander. In addition, it also introduces the application status and potential utilization of screw expander.

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Rare Earth Elements and Other Critical Metals in Deep Seabed Mineral Deposits: Composition and Implications for Resource Potential

Minerals ◽

10.3390/min9010003 ◽

2018 ◽

Vol 9 (1) ◽

pp. 3 ◽

Cited By ~ 3

Author(s):

Sang-Joon Pak ◽

Inah Seo ◽

Kyeong-Yong Lee ◽

Kiseong Hyeong

Keyword(s):

Rare Earth ◽

Deep Sea ◽

Mineral Resources ◽

Rare Earth Oxide ◽

Economic Feasibility ◽

Mineral Deposits ◽

Low Grade ◽

Ion Adsorption ◽

Critical Metals ◽

Deep Sea Sediment

The critical metal contents of four types of seabed mineral resources, including a deep-sea sediment deposit, are evaluated as potential rare earth element (REE) resources. The deep-sea resources have relatively low total rare earth oxide (TREO) contents, a narrow range of TREO grades (0.049–0.185%), and show characteristics that are consistent with those of land-based ion adsorption REE deposits. The relative REO distributions of the deep-seabed resources are also consistent with those of ion adsorption REE deposits on land. REEs that are not part of a crystal lattice of host minerals within deep-sea mineral deposits are favorable for mining, as there is no requirement for crushing and/or pulverizing during ore processing. Furthermore, low concentrations of Th and U reduce the risk of adverse environmental impacts. Despite the low TREO grades of the deep-seabed mineral deposits, a significant TREO yield from polymetallic nodules and REE-bearing deep-sea sediments from the Korean tenements has been estimated (1 Mt and 8 Mt, respectively). Compared with land-based REE deposits, deep-sea mineral deposits can be considered as low-grade mineral deposits with a large tonnage. The REEs and critical metals from deep-sea mineral deposits are important by-products and co-products of the main commodities (e.g., Co and Ni), and may increase the economic feasibility of their extraction.

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