Conference Paper

INTEGRATION OF RENEWABLE ENERGY IN THE PRODUCTION SCHEDULING PROBLEM USING GRAVITATIONAL SEARCH ALGORITHM

Authors:
  • Islamic Azad University | IAU · Faculty of Technology and Engineering
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Abstract

The mining industry has traditionally relied on conventional fossil-based fuel sources to meet its growing energy demand. The industry is now tasked with responding to the challenges of increasing fuel prices while commodity prices tighten, resulting in ever-narrowing operating margins and increased opposition from communities to new conventional energy sources. So far, research about such decision-making on the use of renewable energy in production scheduling (PS) problem for open pit mining operations is underdeveloped. Due to the conflicting nature of economic and environmental objectives, the PS becomes a multi-objective problem. In this paper, a multi-objective gravitational search algorithm is used to provide Pareto optimal solutions which present the possible tradeoff between the cost and environmental objectives of the PS problem. To solve the problem, the weighted sum method is applied to convert multi-objective optimization to scalar optimization. The numerical results demonstrate the effectiveness of the proposed approach in solving multi-objective PS problems.

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The present study investigates the effects of feeding properties on rock comminution by a laboratory scale jaw crusher. For this purpose, detailed crushability tests were carried out on four different rock types to assess their degree of rock crushability (DRC). Various feeding sizes (9.5 – 19 mm) and quantities (500 – 1500 g) were adopted to reveal the choke feeding intensity during crushing actions. The efficiency of feeding properties was investigated through the response surface methodology (RSM). The RSM results demonstrated that the characterized feeding size (F80, mm) dominates the general size reduction, whereas the feeding quantity (mf, g) is associated with the crushing energy consumption and product flakiness. Therefore, the choke feeding intensity has a direct relation to the mf and F80. In addition, novel gene expression programming (GEP) models were employed to generate empirical formulations to predict the DRC parameters. The established GEP models have a satisfactory estimation capability. Therefore, the DRC of the investigated rocks can be optimized through the proposed GEP models based on the coupling variables of mf and F80.
Article
The Reflux Flotation Cell (RFC) utilises the Boycott Effect to decouple the overflow water flux from the gas flux, permitting in principle high product grade and recovery at a vastly higher volumetric feed flux. This study investigated this relationship between concentrate grade, recovery, and volumetric feed throughput using a single flotation stage and feed fluxes spanning 1–9 cm/s, well beyond that used in conventional flotation. Coal flotation tailings and hydrocyclone overflow provided convenient representations of “binary” feeds for the experiments, constituting liberated hydrophobic and hydrophilic particles. The results demonstrated robust recoveries through the preservation of the gas to feed flux ratio with increasing feed flux, while minimising the gas flux strengthened the capacity to maintain high product grade using inverted fluidization water as the wash water. Remarkably, a high product grade (low product ash%) was maintained over the extreme feed flux range by ensuring a net downwards flux of wash water delivered through the upper fluidized bed of bubbles. Coal Grain Analysis (CGA), an optical imaging technique, identified the maceral composition of the feed particles and validated, with close agreement, the RFC steady state separation performance. Indeed, under continuous operation the RFC data demonstrated an overall positive shift in performance relative to that of the standard tree flotation curve. The findings showed strong preservation of product grade and recovery using a single RFC stage, over a seven-fold increase in the feed flux relative to conventional flotation systems.
Article
There is an emerging importance for improving the productivity of sandy soils, and enhancing the efficiency of feeding use, especially with the newly reclaimed soil in Egypt. The present study aims to assess the influence of bentonite and nano bentonite application on the physical and chemical properties of sandy soils. Nano-particles of bentonite were prepared by Sonochemical,and bentonite and nano bentonite were characterized by (XRD), (XRF), (AFM), surface area and (FTIR). Field and pot experiments were carried out for studying the impact of adding bentonite (T1)5 ton ha 1 , (T2) 10 ton ha 1 and nano bentonite (T3) 250 kg ha-1, (T4)500 kg ha 1 on some sandy soil properties and its nutritional states; Total porosity (TP); Bulk density (Bd); available water (AW); water holding capacity (WHC) and availability of macronutrients. Data indicated that addition of bentonite and nano bentonite resulted in an increase of available water (AW) and water holding capacity (WHC), compared to the control in pot and field experiments (surface 0 20 cm). The increase in AW and WHC was highest at T4, and lowest at T1 treatment. Results showed that T4 treatments significantly increased the biological yield, grain yield and (100-grain weight, 1000-grain weight) of wheat, in comparison to all the treatments in both experiments. The best treatments of nano bentonite were ultimately T4, followed by T2 of raw bentonite, which gave the highest values of elements content (N, P and K) in the soil or grain and straw of wheat crop whether in pots or in field experiments
Article
The second of three new textbooks in the field of Theory and Practice of Sampling.
Article
Hydroxyapatite ceramics derived from organic materials have similar physical properties and chemical content to stoichiometric hydroxyapatite ceramics produced via synthetic routes. The focus of the current study is to produce hydroxyapatite ceramics from meagre fish bones via calcination method. To the knowledge of the authors, this is the first report in which the meagre fish bones are used to produce hydroxyapatite. The effect of calcination temperature on the phase content, chemical composition, microstructure, and cytotoxic properties of hydroxyapatite ceramics produced from the bones of meagre fish, Argyrosomus regius, was investigated. Thermogravimetric-differential thermal analysis of the raw fish bones was performed over a temperature range of 20–1100 °C under air atmosphere with a heating rate of 10 °C/min. The total mass loss at this temperature range was about 59% for the fish bone. Thermal analysis of the sample exhibited a three major weight change stage. Calcination was performed in an air atmosphere at different calcination temperatures ranging from 800 to 1100 °C for 1 h. XRD analyses of the calcined fish bones revealed that the hydroxyapatite and whitlockite phases were formed at all calcination temperatures. Significantly marked alterations were observed at the microstructure of the samples depending on the calcination temperature. Scanning electron microscopy investigations revealed that nanocrystalline hydroxyapatite particles were achieved at 800 °C. As the calcination temperature was increased, particle size of the calcium phosphate phase was also increased and reached to approximately 1 μm for the sample calcined at 1100 °C. Cytotoxicity evaluation of the hydroxyapatite carried out using XTT assay demonstrated that the materials are non-cytotoxic at concentrations up to 100 mg/ml.
Article
This study aims to explore the feasibility of using waste red clay from a sedimentary, interlayered phosphate deposit to produce a geopolymer mortar without any pre-treatment. Alkali activated mortars were prepared by mixing fly ash or slag with red clay and sand, using different fly ash or slag/red clay ratios. The effects of sodium silicate to sodium hydroxide ratio (SS/SH) and curing time on the mortar's properties were studied. The results showed that compared to fly ash-based alkali activated materials, an increase of the slag content resulted in the formation of dense mortars while in the case of fly ash based-samples more porous mortars were formed when the fly ash amount was increased. The mineralogical investigations indicated a partial contribution of montmorillonite and palygorskite from the clay to the alkali activation reaction. The mechanical properties of the materials were promising with a maximum compressive strength of up to 39 MPa obtained for the mixture of fly ash and red clay at a fly ash/red clay ratio of 2 and a SS/SH of 1.
Article
This study aimed to estimate the impact of an abandoned copper (Cu) mine on ecosystem environmental quality, using integrated ecological and biogeochemical analyses. Through a controlled experiment, the amount of Cu released by waste rocks, Cu adsorbed in soils, Cu geochemical behaviour and its leached amount were measured. Furthermore, to investigate the impacts of mine drainage on the adjacent ecosystem, samples of sediments, water and aquatic macroinvertebrates were analysed. We found that waste rocks still have high Cu concentration even after 30 years under weathering, ranging from 7,782 to 8,717 mg kg⁻¹, associated mainly with carbonates, amorphous oxides and sulphides. It was estimated that 7.2 tonnes of Cu were released by waste rocks into the environment over last 30 years. The concentration of Cu observed in Ubari stream water was (<dl to 90 μg L⁻¹), in sediments (28.0 to 1,185 mg kg⁻¹) and in macroinvertebrates (1.3 to 28.9 mg kg⁻¹ d/w). The ecological indexes showed that near mine discharge a significance decrease in the density of aquatic macroinvertebrates and a significance increase of Cu in biological tissues occurs, causing disturbances in biodiversity. The results showed that, even after long periods, the waste rocks from abandoned mines still contain high levels of metal, that are gradually released into the environment through weathering and erosion, representing a potential source of environmental pollution and a clear threat to the environmental quality of adjacent ecosystems.
Article
The production of construction and building materials starts with reducing the size of natural, industrial, and waste materials. In addition to strength and durability considerations of natural resources recommended by various institutions, size reduction characterization, specific to rock aggregates, has a vital role in their size-related quality. In this study, various sandstones extracted from underground mines located in northwestern Turkey were investigated for size reduction characterizations. Several mineralogical, textural, and physico-mechanical properties were determined for each rock type. Crushability tests were carried out using a laboratory-scale cone crusher for different feeding size fractions, namely + 11.20 − 16.00 mm (size I), + 9.52 − 16.00 mm (size II), and + 6.30 − 16.00 mm (size III). Based on the crushability tests, crushed particles were analyzed, focusing on production yield, size, and shape properties. Each crushability test was also explored for energy consumption arising from varying rock properties of the sandstones. The laboratory test results demonstrated that the degree of rock crushability (DRC) and specific energy consumption (Ecs, kJ/kg) were associated with the Brazilian tensile strength (BTS, MPa) and apparent porosity (ne, %) of the sandstones. The results also showed that the degree of sorting in mineral constituents, quantified as the sorting coefficient (Sc), affected the DRC. However, mineralogical features of the sandstones have no significant impact on DRC and Ecs. Variations in feeding gradation, irrespective of whether mineralogical, textural, or physico-mechanical properties, have remarkable effects on product flakiness and yields for specific size fractions. In light of the findings obtained, the present study provides knowledge on how the sandstones behave under cone crushing operations.
Article
The size reduction process of rocks in cone crushers is one of the most important issues, particularly for the secondary and tertiary stages of crushing operations. In this study, 17 different rock types were considered for the evaluation of their size reduction variations that occurred in a laboratory-scale cone crusher. Based on several mineralogical, physico-mechanical, and aggregate properties determined for each rock type, the crushability tests were performed.Before and after the crushability tests, particle size distribution (PSD) of the uncrushed (feed) and crushed (product) materials were determined by sieve analyses. On the basis of these PSDs, the degree of rock crushability (DRC) was attempted to quantify by simple approaches (i.e., size reduction ratio, SRR, and the theoretical square mesh aperture size that corresponds to the 10% of the cumulative undersize in the product, P10 (mm)).The crushability test results demonstrated that the DRC in cone crusher could be quantified by focusing on the variations in the SRR and P10. The SRR and P10 are associated with three important rock properties, Shore hardness (SH), Los Angeles abrasion loss (LAA, %), and Brazilian tensile strength (BTS, MPa). The textural and mineralogical features of rocks also have substantial impacts on the DRC for several rock types. It was concluded that the combination of the SRR and P10 could be considered together for the evaluation of DRC in cone crushers. Moreover, further research potentials on the DRC were also discussed in this study.
Article
The Reflux Flotation Cell (RFC) consists of a vertical vessel located above a series of parallel inclined channels. This novel system, which is the inverse of an existing gravity separation system known as the Reflux Classifier, provides a powerful mechanism for enhancing bubble-liquid segregation. The usual link between the imposed gas flux and water recovery in the froth product is decoupled through this mechanism, resulting in the establishment of a concentrated bubbly zone throughout the upper section of the cell, and no froth zone. A downwards fluidization arrangement promotes strong washing of the flotation product, to remove the hydrophilic slimes from the hydrophobic concentrate. The mechanism also provides for strong control of the bias flux, allowing a significant positive bias flux to be established. A feed suspension of fine coal tailings containing hydrophobic coal and hydrophilic mineral matter was subjected to the novel flotation, providing an ideal basis for studying the interplay between the hydrophobic particle recovery, inferred by the combustible recovery, and the product grade, inferred by the mineral matter content of the product, expressed by the ash %. The feed ash % was about 43 wt%. The product cleaning was compared to firstly, the results from the tree flotation method, and secondly, a newer method known as Coal Grain Analysis (CGA). The RFC results were found to lie to the left of the tree curve, converging to the limit described by the CGA analysis. This work suggests the RFC and CGA provide a form of mutual validation on the limits of cleaning, though more work will be needed to confirm this finding. The RFC was operated with a volumetric feed flux of the order 1 cm/s, a rate comparable to that of conventional flotation systems, with the bias flux ranging from 0.0 cm/s to 1.9 cm/s. For a fixed gas flux of 1.1 cm/s, increases in the liquid bias flux from 0.0 cm/s to 1.0 cm/s resulted in a decrease in product ash from 18.2% to 7.8%, and a reduction in combustible recovery from the order 87% to 75.6%. Operating at the lowest gas flux of 0.6 cm/s, and the strongest bias flux of 1.9 cm/s yielded a low product ash of 6.7% at the reduced combustible recovery of 64%.
Article
With the vigorous development of lignite in the global region, the upgrading technology of lignite has gradually matured and a large amount of pulverized coal is produced during the upgrading process. And the pulverized coal is special in nature and difficult to process and utilize. In this paper, the briquetting of upgraded lignite powder was carried out by cold pressure methods with external binder. Response Surface Methodology (RSM) by Design Expert software was used to analyze the briquetting of the upgraded lignite powder with PVA solution as binder. It revealed that the interaction between the molding pressure and the amount of water addition as well as the drying time and the binder mainly affected the falling strength of briquettes. Regression analysis indicated that the optimum molding conditions were: 19.70 MPa of molding pressure, 0.52% of PVA binder addition, 21.61% of water addition and 5.65 h of drying time. Simultaneously, the predicted value of falling strength of the model is 98.67%. This is close to the experimental value (98.72%). The analysis of wettability, SEM and zeta potential shows that these briquetting conditions can make briquettes better.
Article
The present work initially studies the impact of a laboratory microwave (MW)’s location (before and after a jaw crusher) on grindability of a copper ore. Additionally, the role of MW’s radiation time (15–150 sec) and grinding time (13, 15 and 17 min) on the produced particle size distribution (PSD), mineral liberation degree (LD) and energy consumption are investigated. relative work index (RWI), standard Bond work index (Wi), and grindability index (GI) together with the breakage and selection functions were utilized to assess the grinding efficiency and its kinetics of the untreated and MW-pretreated (at a constant power of 0.9 kW) samples. Bond work indices were obtained 13.70, 13.04 and 10.86 kWh/t for the untreated, MW-treated uncrushed and MW-treated crushed samples, respectively. Besides, the results confirmed that the microwave pretreatment was comparatively effective at the shortest grinding time (13 min). Furthermore, locating the microwave after the crushing stage indicated substantial improvements in the sample’s grindability and its kinetics rate. The product size (P80) of the MW-treated crushed sample (13 min, 0.9 kW, 150 sec) showed enhancements of 27% and 17% in comparison with the un-microwaved and MW-treated uncrushed samples. Finally, the comparative GIs acquired in the entire spectrum of the particle range were reasonably higher if the microwave was located after the jaw crusher, particularly for the coarse fraction sizes.
Article
Brazil is one of the world key players in the mining industry. This sector has also a remarkable role on the Brazilian economic and social development. Nonetheless, the economic, social and environmental impacts of the sector have not yet been fully documented, debated or understood in reports presented by companies and public organizations in the country. In this context, this research aims to contribute to this debate by analysing sustainability in the Brazilian mining sector. For this research, the approach has used mostly a qualitative method, interviews, coupled with content analysis of reports of public mining agencies. Results showed that sustainability assessment and communication is still an emergent process in Brazilian mining, since only a few large companies have been reporting their sustainability initiatives. The results provide also evidence of the existing gap between large and small companies, with the latter showing lower levels of awareness of the impact of their activities. Based on these findings, this research has concluded on the need for closer cooperation between government, public mining agencies and companies to raise levels of knowledge and awareness within companies, towards sustainability practices and communication initiatives.
Article
The purpose of this study was to investigate the effects of conventional flotation and simultaneous ultrasonic flotation in the pulp/froth zones on the separation selectivity and kinetics of high-ash lignite flotation. Particularly, the mechanism of ultrasonic flotation in the froth zone, which improved the flotation performance of lignite, was elucidated. Flotation tests, wet screening, SEM, and froth layer observation tests were employed to reveal the mechanism by which simultaneous ultrasonic flotation improved lignite flotation. The flotation results indicated that the lowest concentrate ash content was obtained using ultrasonic flotation in the pulp zone, while the highest concentrate yield and water recovery were achieved using ultrasonic flotation in the froth zone. The wet screening and SEM results indicated that ultrasonic flotation in the pulp zone afforded the best surface cleaning on the coal surface, which significantly improved the flotation selectivity of lignite. Ultrasonic treatment in the froth zone produced large bubbles and a thin froth layer due to ultrasonic cavitation and oscillation, thereby improving the recovery of fine particles by water entrainment. However, simultaneous ultrasonic treatment in the froth zone did not improve the separation selectivity of lignite flotation. In addition, the second-order model with rectangular distribution of floatability provided the best fit with the experimental data of all the flotation types, based on the analysis of the model fit and stability. Notably, the flotation rate constants of ultrasonic flotation in the froth and pulp zones were 1.8981 min⁻¹ larger and 1.476 min⁻¹ smaller, respectively, than those of conventional flotation.
Article
Environmental impacts from the mining is so diverse in nature that it requires different tools to quantify. Life Cycle Assessment (LCA) is one of the popular tools that can assess the impact of mining activities. Remote sensing (RS) based imagery analysis helps to explore the change in earth surface by providing long-term historical data which is very useful for mining induced environmental impact assessment. Therefore, we used the knowledge of RS based image analysis to analyze the direct footprint of mining that is the land use change. Besides, we also used LCA to quantify the environmental impacts focusing mainly on Global Warming Potential (GWP) and Gross Energy Requirement (GER). The case study site was a copper-gold-silver mine located in Laos, called Phu Kham mine. The RS based image analysis suggests that the land use change due to mining during 2007–2018 was approximately 3.98 km2 whereas the overall intensity of land use change in the same period was about 0.0052515 m2/kg of concentrate. We also analyzed the indirect CO2 emission from vegetation lost by mining. The GER of the mine showed average value for an open-pit copper mine though the CO2 emission was lower mainly due to the use of hydroelectricity. We also tried to quantify the productivity of the mine site. The findings from this study was also compared with existing literature. Though the impact of the mine was lower, there is room for improvement. We have tried to provide a few directions for that as well.
Article
Cleaner production is the continuous application of an integrated preventive environmental strategy which stressed the importance of environment and human beings. Although the application of cleaner production is becoming more and more mature in different industries, since the complexity of the mining operation itself and its extensive and complex impacts on the ecological environment, the application of cleaner production in the mining industry encounters great challenges. For this purpose, the paper presents some developments and new insights of environmental problems and deep mining strategy for cleaner production in mines. Firstly, the general impacts on the ecological environment of mining industry and the current corresponding solutions as well as future prospects are presented. Secondly, the ecological environment pollution induced by tailings dam and its elimination approaches are reviewed. For the accelerating volume of tailings dam waiting to be processed, the exploration and research of the comprehensive utilization and treatment of tailings is expected to be more effective with larger consumption and wider range of application. The development direction is the establishment of mine without tailings. With the development of modern technology, some intelligent monitoring and warning technologies have helped the mining engineers to keep a vigilant eye on tailings dam continually. Finally, to convert the “harm” of four highs and one disturbance induced by the complex mechanical environment in deep mines into “benefit” various specific measures with relatively high novelty and sustainability are recommended. Moreover, the conception map of safer and more efficient exploitation of resources in deep mines is depicted for industrial best practice and future research directions to enhance cleaner production work in mining.
Article
Wide application of the Tafel extrapolation method (TEM) for the estimation value of the exchange current density (i0) on the hydrogen evolution reaction (HER) is still hindered because of some issues. For example, a possibility of improper reading of the tafel slope and the physical resistant such as an oxide film on electrode and solution resistance which requires more consideration in the calculation. The differential polarization method (DPM) was introduced as a reliable method to estimate the value of the i0. In this paper, HER of a copper electrode in 0.5 mol dm⁻³ H2SO4 solution was investigated and compared using both methods. The DPM shows that the undesirable physical factor of copper in the measurement could be removed rationally and is acceptable on the calculation of i0. Moreover, the tafel slope region could be read accurately.
Article
Lead alloys are used as permanent anodes for electrowinning of base metals such as copper. The corrosion of anodes is costly because of their relatively short lifetime, material cost, and their impact on cathodic deposit quality. Failure of anodes sometimes occurs before the predicted lifetime, having a negative impact on the efficiency and economics of the electrowinning process. This study investigates some recently failed lead alloy anodes. These failures occurred after a short period of service in a commercially operating electrowinning tank house. The samples were metallographically investigated with the help of an optical, three-dimensional microscope and a scanning electron microscope (SEM) equipped with Energy-Dispersive X-ray Spectroscopy (EDS) analysis. It is suggested that the reasons for failure are improper operational issues in the tank house, especially the level of manganese content in the electrolyte, which leads to unexpected corrosion.