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By S. Green, R. Yang

Blasting is a commonly used method for rock fragmentation in mining operations for mineral extraction. It involves breaking the rock mass into small pieces, and ideally creating micro fractures within the small pieces. Such micro fractures could significantly reduce the energy required for subsequent processes like crushing and comminution. Additionally, micro fractures would enhance the rock-fragraments fluid permeability thereby enhancing desired chemical reactions during certain processing operations. This paper presents recent developments of the Multiple Blasthole Fragmentation (MBF) model, which simulates blasting rockmass fragmentation. The MBF model allows estimating rock strains experienced during the blast, for various blast design parameters and geometries. The intent is to correlate these strains with created micro fractures in the blast rock fragments. Adjusting blast design parameters in the MBF model of explosive loading and delay timing allows blast optimization. Such optimizing would create desirable strains to enhance micro fractures within the rock fragments. This would improve mining operations by enhancing downstream operation efficiency, thus reducing costs.

Jan 1, 2024

By D. Johansson, C. San Miguel, U. Stenman, N. Petropoulos

Blasting is a commonly utilized method in civil engineering projects and mining operations. Ammonium nitrate-based (AN-based) explosives are the most efficient explosives today in terms of handling and performance. However, a side effect is the production of gases. The reduction of these gases plays an important role in the safety and environmental aspects in the working place. Therefore, optimizing the recipes of explosives is vital for minimizing the environmental impact and increasing performance. The aim of the project is to provide results and recommendations on the use of emulsion commercial explosives to support the Swedish mining industry and tunnel-contractors as well as the explosives manufactures. The approach was to test various recipes of civil emulsion explosives to investigate the generation of toxic fumes (CO, CO2, NO, NO2 and NOx) during their detonation. To further increase the knowledge of the influence of different additives, ammonium nitrate prills were added in various percentages. The experimental configuration consisted of magnetite mortar cylindrical specimens with a 50 mm borehole at their center, filled with emulsion explosive. Several tests with different emulsion compositions regarding ammonium nitrate additives (10%, 20%, 25%, 30% and 35%) were carried out in a blasting chamber. The measurement equipment was composed of a flue gas analyzer. The instrument was meticulously cleaned after every test, as well as before and during the tests due to condensation (high humidity and dust) at the inlet of the instrument. The emulsion was manually sensitized with microballons and pumped into the cylinders to ensure lack of bubbles, which could introduce inhomogeneities. The acquired gas concentration data was complemented with temperature, humidity, and VoD measurements. The results showed a linear increase of nitrogen gases as the percentage of ammonium nitrate prills increased. On the other hand, carbon gases had a relatively low coefficient of determination. The VoD data showed a behavior that can be described with a simple quadratic equation.

Jan 1, 2024

By S. Hosein, W. Birch, C. Johnson

The widespread adoption of electronic detonators has given rise to the development of linear superposition to control the environmental impact on both third-party properties and residents resulting from blast induced vibrations. Linear superposition has become a very effective tool in the hands of blasting engineers and has enabled aggregate reserves to be accessed that once had to be abandoned. This in turn has resulted in more and more complex blasting pattern to be developed that contain multiple rows and multiple decks all with different maximum instantaneous charge weights of explosives. This is then made more complex by having to consider multiple sensitive locations often with different Peak Particle Velocity vibration limits. This paper is a case study of what did happen when a blast was designed that “pushed the boundaries” of environmental blast vibration design and control, without taking fully into account the fundamental geophysical properties of seismic waves. The resulting blast design caused a greatly enhanced s-wave to be created in a critical direction from the blast pattern. The root cause being the s-waves from earlier detonating decks in the blast pattern arriving within 2 milliseconds of decks detonating later in the blast pattern. 209 individual decks were fired in the blast pattern of which 41 pairs of decks arrived at the observation location less than 2 milliseconds apart when taking into account the s-wave speed and direction. The lesson to be learned when using electronic detonators to limit ground vibrations from complex blasting patterns, is that it is just not good enough to look at the planned firing times, a professional blasting engineer must also understand the likely interaction of the various seismic wave types created and their combined impact on any given monitoring location.

Jan 1, 2024

By D. Swanson

Cold Detonation Physics (CDP) is a patented new field of explosives and the name for the explosive that is produced when non-toxic dry ice (frozen carbon dioxide) is combined with powdered metals such as magnesium and aluminum, which are non-toxic and nitrogen-free. The explosive is detonator-sensitive and detonates according to the rapid reduction of carbon dioxide back to carbon, which produces solids comprised mainly of metal oxides and about 5% carbon. CDP was determined to produce a maximum of 300 liters of carbon dioxide per kilogram (4.81 ft3 /lb) and about 1.5 liters of carbon monoxide per kilogram (0.024 ft3 /lb). Both these figures shift according to metal content where higher metal produces less gases. According to theoretical modelling, the relationship between static pressure and metal content was determined to be an inverse parabolic curve with optimum pressure at 25% to 31% metal, depending on the type/s of metal/s used. Velocity of Detonation (VOD) was determined by measuring light at the wavefront with fiber-optic cable inserted into a series of holes drilled into the side of a 3-inch diameter (76 mm) schedule 40 steel pipe containing the mixture. The highest VOD was observed at 25% magnesium and measured between 2,500 to 4,500 m/s (8202 to 14,764 ft/s) when initiated by a 454-gram (1-pound) booster and an electric detonator. A 25% 50:50 alloy of magnesium and aluminum sample shot at a higher velocity than magnesium, according to how the alloy generated smaller pieces of shrapnel when compared with shrapnel from a magnesium test. CDP, using 25% alloy, was tested for blasting limestone by drilling 3.5-inch holes (89 mm) and inserting a 3-inch x 4-foot cardboard tube (76 mm x 1.22 m) with the mixture, packed to a density of 0.62 g/cm3 . The blast was initiated with an electric detonator, behaved like ANFO with more energy and fractured rock sufficiently across the entire length of the borehole. Seismic analysis determined that CDP produces lower ground vibrations than traditional explosives.

Jan 1, 2024

By R. J. Cefalo

Blast and mining spillover between phases or critical areas of the pit is a continuing problem in the mining industry and a safety concern for operating mines. The challenge for many mines is to produce the highest value in the shortest amount of time for any project. For any project, the top priority of any mine is producing ore as fast as possible. The next challenge is to keep that ore feed continuous. To achieve continuous ore feed, pits are designed with multiple phases that are connected and are mined at different elevations. This difference in elevation causes dangers with spillover between the phases during mining, drilling, and blasting. This paper covers an incident that occurred at an active mine and the work completed in creating a spillover control program over an active mining phase. The drill and blast technical group was responsible for creating blast patterns to reduce spillover between these phases. Unrealistic goals and expectations were initially set for the area of the pit. The drill and blast technical group needed to figure blast objectives and work with the geotechnical team to align with these goals. This paper will go over the executed example of setting up spillover targets and expectations for multiple sections of an operating mine. Different sections of the pit had different control measures and blast objectives due to narrow laybacks and double benching. The use and value of blast objectives and goals were beneficial in setting expectations and measuring design success. Having unrealistic blast goals can set up the operations to fail or get frustrated in trying to work on an impossible task. The problems and risks of phase interactions for many open pit operations need to be considered in the design process, along with designed controls that minimize the probability of any safety incident. Mine designs are being created in the industry and do not consider phase-to-phase mining interaction and the impact it would have on safety or production. The best future for safer mines is blast patterns that reduce spillover between phases of mining and pit designs that might account for spillover interaction.

Jan 1, 2024

By K. Best, D. Conn

The US Army Corps of Engineers KY Lock Project in western Kentucky presented the blasters and vibration consultants with a set of unique challenges. The blasters on this project were faced with difficult geology and joint set orientation and sequencing of blasts opposite from what the explosive engineer/blasting specialist had recommended. Combining these issues with strict vibration and air overpressure specifications, blasting as close as 7 feet (2.1 meters) from a new lock wall, site topography that influenced the air overpressure, limitations on seismograph geophone placement that led to anomalies in seismograph recordings; surprising lessons were learned by everyone involved in the project and it is the authors’ goal to share this valuable information with everyone in the blasting industry.

Jan 1, 2024

By M. Szumny, P. Mertuszka, K. Fuławka

Multi-face destress blasting is the basic method of reducing rock bursts hazard in Polish copper mines. Blasting operations of this type are carried out regularly, twice a day in order to minimize the geomechanical threat while maintaining high extraction efficiency. Unfortunately, the assessment of the effectiveness of this type of work until recently was based solely on determining whether a given destress blasting triggered a seismic tremor or not. Information on the characteristics of seismic waves generated by blasting has so far been omitted in analyzes of this type. The lack of reliable knowledge about the generated seismic effect makes the introduction of constructive corrective actions impossible, which in turn significantly reduces the triggering potential of conducted destress blasting. This study presents the results of comprehensive work aimed at increasing the effectiveness of active rock burst prevention in Lubin underground copper mine. For this purpose, an innovative system for continuous monitoring of seismic waves induced by multi-face blasting was developed, and a new method for seismic assessment of the effectiveness of the destress activities was developed. Based on the monitoring data and the comprehensive analysis of waveforms, the effectiveness of individual blasting operations was determined, and on this basis, modifications to the drilling and blasting patterns aimed at increasing the generated seismic effect were proposed. The use of innovative methods of monitoring and data analysis made it possible to increase the effectiveness of the conducted activities, in terms of the magnitude of seismic vibrations, up to 250%. It should be emphasized that the introduced modifications were aimed at increasing the effectiveness of blasting operations while maintaining the current level of costs. As a result, the proposed solution turned out to be highly effective, significantly affecting the safety of the work carried out in Polish copper mines. Thus the proposed approach is planned to be implemented in other Polish copper mines belonging to KGHM in the near future

Jan 1, 2024

By AMIR EHSAN KIANFAR, Moritz Ziegler, TOBIAS HARTMANN, ELISABETH CLAUSEN

Accurate positioning information is a central step in the process of increasing automation and digitalization in the mining industry. Underground mine environments are prime examples for GNSS-denied environments that pose several additional challenges for the employed indoor positioning system (IPS). This work presents an ultra-wideband (UWB)- based system specifically tailored for underground mine environments. Initially, the UWB technology is reviewed and basic concepts of IPS are explained. Both software and hardware are described in detail, including positioning algorithms, electrical circuitry and the mining-compatible enclosure. Finally, the results from field tests in an underground mine are presented and positioning performance and the influence of dilution of precision (DOP) on positioning results are empirically evaluated. The results show that the localization errors are mostly below 1 m. Individual zones of high localization errors are suspected to be caused by noise interference. Significant DOP influence due to the mining drift geometry can be confirmed. The system shows promising localization results for different mining applications, while influences negatively impacting the accuracy are presented as items for future research.

Jan 1, 2024

By Mustafa Kumral, Yuksel Asli Sari

Economic evaluations of underground mining operations are made based on the estimated or simulated grades of the block model as the actual values are not known. Depending on how the planning decisions are made, the risk of the operation can be managed and decreased. This research introduces a mixed-integer linear programming (MILP) model for stope sequencing optimization that considers the uncertainty associated with net present value (NPV) using chance-constrained programming (CCP). The introduced method permits achieving a balance between maximizing NPV and reducing the associated operational risk through transforming the problem into a multiobjective problem, where the objectives are maximizing the NPV and minimizing the risk. This risk is expressed in terms of the standard deviation of project outcomes, taking into account multiple possible scenarios. In a case study, the efficiency of the method was demonstrated as a decision-making tool capable of translating a specified risk or reliability level into a stope sequencing plan.

Jan 1, 2024

By Shangyong Lin, Wei Sun, Weiping Liu, Muhammad Azam, Junfeng Cheng, Yujie Zhao, David Asubonteng, Michael Ngoie

Copper concentrates have wide application in global smelting operations, comprising primarily of chalcopyrite (CuFeS2) as the principal mineral, accompanied by chalcocite (Cu2S) and bornite (Cu5FeS4) as secondary copper-bearing minerals. However, these concentrates frequently harbor detrimental impurities, notably fluorine ions, which can cause various complications during the smelting process. Moreover, an elevated fluorine content in copper concentrates may entail financial penalties and sales constraints. This review conducts a comprehensive analysis of existing methods for the removal of fluorine, presenting a nuanced assessment of their merits and demerits. It also provides valuable insights into the current landscape of fluorine elimination from copper concentrates and pinpoints pivotal areas warranting future investigation. This review endeavors to serve as a pragmatic resource for researchers and industry professionals operating within this domain.

Jan 1, 2024

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES

Lithium-ion (Li-ion) battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12 V and 24 V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicate that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Jan 1, 2024

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By Chunhui Zhang, Enton Bedini, Jiang Chen, Fengchao Yang, Hang Dong, Xiaoyan Chen

The alteration formed by the reaction of ore-bearing fluid and wall rock is often used as an important prospecting indicator, resulting in the dilution or enrichment of metals or related trace elements. A variety of rock-forming and metallogenic elements have been analyzed in regional stream sediments so that the relationship between the ore-bearing altered rock and the change in the geochemical elemental content can be obtained. Therefore, by using appropriate models, such as matched filtering, the abundance of the distribution of wall rock alteration, similar to the discovered deposits, can be modeled by using the distribution of geochemical elements in the region, and the areas with high distribution abundances are usually favorable prospecting targets. The alteration types related to gold mineralization in the Baiyun gold deposit are potassium feldspar alteration, silicification, pyritization, sericitization, and chloritization. In this paper, the geochemical data of the Qingchengzi ore field (1:200,000 and 1:50,000) have been used to form geochemical images through rasterization. In the three sections of the Baiyun gold deposit, binary-coded curves have been formed, revealing the differences in geochemical elements in stream sediments between altered rocks and the rocks surrounding the Baiyun gold mine. Among them, Au, W, and Mo are enriched elements, while Sn, Zn, and Hg are depleted elements. Several gold deposits are found in the predicted altered rock area by using the matched filtering method during fieldwork, which shows the effectiveness of the method.

Dec 30, 2023

By Arif Emre Dursun

The aim of this study is to present hazard classifications of location, type, and causes of accidents in Turkish coal-extracting industries using Analytic Hierarchy Process (AHP). In this study, fatal mine accidents were analyzed by pairwise comparison and weighting, and the most important hazards were identified by determining the effective main and sub-criteria among location, type, and causes of accidents. For this purpose, 1st, 2nd, and 3rd level hazards consisting of location, type, and causes of accident were determined by using the data of fatal mine accidents in underground and open-pit coal mining in Turkey between the years of 2010 and 2020. And then the data were categorized, and each category was prioritized using the AHP technique. According to the weights calculated by AHP, the most dangerous main criteria at 1st level hazards in underground coal mining is ventilation operations (0.363), while the most dangerous sub-criterion at 2nd level hazards is firedamp explosions and other gas accidents (0.409). On the other hand, in open-pit coal mining, the most dangerous main criteria at 1st level hazards are slopes and benches (0.575), while the most dangerous sub-criterion at 2nd level hazards are landslides (0.429).

Dec 30, 2023

By Hasan Ali Taner, Vildan Onen

One of the problems in flotation is mechanical entrainment and the other is the presence of complex gangues (especially clay minerals). In the present study, it was aimed to determine the effects of clay types (kaolinite, illite, and montmorillonite) on mechanical entrainment parameters (total flotation recovery, real recovery, mechanical entrainment recovery, and water recovery). Effects of clay types and clay amount on chalcopyrite flotation were investigated by flotation experiments. Interaction mechanisms between the clay minerals and ore were characterized using SEM–EDS analyses. Experiments were carried out with and without a collector using the mixture of clay minerals and ore under certain experimental conditions. While the clay mineral most affecting the chalcopyrite grade was montmorillonite, the highest mechanical entrainment recovery and the lowest real recovery values were obtained in the presence of illite. While illite is stated as the least problematic clay mineral in the literature, it was determined that illite among three clay minerals used in this study caused significant mechanical entrainment. In contrast, it was determined that increasing the amount of kaolinite did not have a significant effect on mechanical entrainment. This study’s findings will guide in determining of clay minerals’ effect on gangue entrainment in flotation.

Dec 29, 2023

By Adabala Raja Venkata Sai Naresh, Radhakanta Koner

Particle size distribution (PSD) is an essential parameter in assessing the overall efficiency of blasting operations in mines and the subsequent mine-to-mill process in the mining industry. Despite some drawbacks of 2D image analysis techniques in accurately estimating particle sizes in PSD, the mining industry has relied on them for the last three decades. This study proposes the 3D rock fragmentation measurement (3DFM) technique for deducting the accurate dimensions of 3D rock particles for the PSD. 3DFM has utilized different processing algorithms. Images of different views of the non-touching rock particles of varying sizes have been acquired as a data acquisition step of structure from motion technology for generating sparse point cloud. Dense point cloud reconstruction is used to avail finer details of the point cloud using clustering views for the multi-view stereo algorithm. Random sample consensus (RANSAC) algorithm coupled with an unsupervised classification using the density-based spatial clustering of applications with noise (DBSCAN) classifier is employed to extract the rock clusters from the 3D point cloud. Finally, the accurate rock sizes are derived using the hybrid bounding box rotation identification (HYBBRID) algorithm with a root mean square error (RMSE) of 0.10 cm for length, 0.10 cm for breadth, and 0.32 cm for depth. The PSD of rock fragments obtained from the proposed 3DFM technique is found to be matching with the results of mechanical sieving and manual gauging with an R2 values of 0.98 and 0.99, respectively. The 3DFM method can be considered cheaper, more accurate, and computationally faster in determining the rock dimensions for the PSD determination method to enhance the productivity of the mining industry.

Dec 29, 2023

By Avula Rajashekar Yadav, Sreenivasa Rao Islavath

Barrier pillars and gateroads play a vital role for the safe exploitation of coal from the panel in the longwall workings. The barrier pillars and gateroads are subjected to the front abutment and side abutment loads during the retreat of the panel. These structures may fail if the developed load on them is higher than their strength. The stability of the longwall structures such as barrier, gateroads and face is paramount in extracting the coal from the panel safely. For this, a deep longwall mine in India is chosen for the study using a 3D numerical modelling technique. In this paper, three critical conditions such as scenario 1 (no side goaved-out panel), scenario 2 (with side goaved-out panel) and scenario 3 (with two side goaved-out panels) are taken. For each scenario, five retreat distances such as 100, 125, 150, 175 and 200 m are considered for detailed investigation. The development of vertical displacement in gateroads, vertical stresses on barriers, vertical stress concentration factor, abutment zone and yield zone for longwall face are extracted and analyzed. Also, the safety factor of the barrier and longwall face is estimated considering the Hoek–Brown rock mass failure criterion. From the study, it is observed that the maximum vertical displacement of 121 mm in TG3 at scenario 3 for a retreat distance of 200 m and a minimum vertical displacement of 33 mm in TG2 for a retreat distance of 100 m at scenario 2. The development of vertical stress on the barrier is found to be between 8.78 and 13.40 MPa, and the safety factor of the barrier lies in between 1.56 and 1.80. The study also revealed that the yield zone at the longwall face lies within 2 to 3 m.

Dec 29, 2023

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Morgana Rosset, Bárbara da Rocha Pereira

High-purity alumina finds application in various electronic industry sectors, with approximately 100 million tons of this compound being produced worldwide. Alumina is acquired through the mining process of bauxite, a rock composed of a mixture of minerals such as gibbsite, kaolinite, hematite, and either anatase or rutile. In 2020, both bauxite and alumina were included in the list of critical raw materials. Due to the demand for high-purity alumina production, the development of a methodology to remove impurities present in the leach liquor from bauxite processing by solvent extraction (SX) followed by precipitation has been widely studied. This work aims to obtain high-purity alumina from bauxite by a solvent extraction process followed by a precipitation step from the sulfur leach liquor obtained by the thorough dissolution of Al and Fe from bauxite. Different parameters were evaluated in the SX step, such as extractant type, pH, temperature, and volume-to-volume ratio. The results indicated that using Alamine 336 as an extractant at pH 0 and room temperature led to an extraction of 90% of Fe and 15% of Al. Aluminum sulfate was completely precipitated as aluminum hydroxide and 55% of Fe using NH4OH. After the calcination procedure, obtaining a 99.9% pure alumina was possible without generating a red mud-similar residue.

Dec 28, 2023

By Chamila Jinendra Nanayakkara, Nimila Dushyantha, Amila Sandaruwan Ratnayake, Gayithri Niluka Kuruppu

Rare earth elements (REEs) are key ingredients in many advanced materials used in energy, military, transportation, and communication applications. However, the prevailing geopolitical dynamics and the rising demand for REEs have rendered the reliance on primary REE resources susceptible to future supply disruptions, posing a substantial risk to the availability of these elements for numerous applications. Therefore, it is imperative to undertake substantial initiatives in the extraction of REEs from secondary sources on a large scale to ensure the resilience of the supply chain. Permanent magnets, lighting phosphors, and nickel-metal hydride (NiMH) batteries are among the secondary sources with high potential for sustainable REE extraction. This review assesses the extraction potential of REEs from the aforementioned three secondary sources and their leaching kinetics and thermodynamics aspects. More importantly, state-of-the-art different existing kinetic models employed in rare earth (RE) leaching were well discussed for a better understanding of the REE leaching reactions. Furthermore, the optimized leaching parameters related to this kinetics were described, and various RE recovery methods were comprehensively summarized. These processes facilitate to managing one of the fastest-growing solid waste streams by minimizing environmental impacts and producing critical metals, including REEs via circular economy approaches. The recovery of REEs from secondary sources aligns with numerous United Nations Sustainable Development Goals (SDGs), particularly in the renewable energy sector for climate change mitigation. Consequently, this trash-to-treasure urban mining concept to transforming e-waste into a valuable resource for REE recovery emerges as a pivotal element within the REE industry.

Dec 28, 2023

By NEHA PANDEY, Sunil Kumar Tripathy, ARIJIT BISWAS

Due to the growing market of Electric Vehicles (EVs), there is a rise in battery demand. Nickel can be used as a potential element in cathode for lithium-ion batteries. Nickel can provide thermal stability, high energy density, and conductivity in cathodes of lithium-ion batteries. Low-grade chromite overburden from Sukinda mines contains less than 1 wt% of nickel, which can be utilized to extract nickel. Recovery of nickel from such low-grade overburden can help in value addition. The present study provides deeper insight into the aspects of extraction of nickel product derivatives (NPDs), mainly mixed hydroxide product (MHP), through the hydrometallurgical route. The current study focuses on extracting nickel and cobalt from a mine overburden with 0.41% nickel with major silicate gangue. MHP can be processed further for nickel sulfate production, a potential raw material for cathodes in EV batteries. The study discusses a process flowsheet to recover nickel and cobalt from overburden through atmospheric leaching with pre-calcination. It is observed that the step of pre-calcination improves the effective recovery of nickel from overburden. The leaching reactions are effective at a temperature of 90 °C and 1 atmosphere pressure. The orthophosphoric acid was used as a lixiviant for the selective recovery of nickel and cobalt from overburden. Recovery of nickel and cobalt obtained at optimum conditions is 84.0% and 39.9%, respectively. The iron impurity in the leachate solution is 1.27%. It is concluded that the process with pre-calcination along with acid leaching is effective for extracting nickel and cobalt at atmospheric pressure.

Dec 28, 2023