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By M. Reuter, U. Boin

The target of the current metallurgical industry is to recycle and utilize all their by-products, so as to close the sustainable production loop. Slags are the important wastes and by-products of metallurgical industry, which have been treated, recycled and used worldwide. The present paper summarizes the current status of utilization of the various slags from ferrous and non-ferrous metal production, as well as waste incineration, and recycling of salt fluxes in secondary metal production. In addition, the environmental issues of the metallurgical slags are addressed. The metallurgical oxide slags have stone-like properties and, thus, their major applications are in civil engineering field. The slags should be recycled, modified and processed in a proper way, by taking the environmental impact into consideration. With the treatment of salt slags for melting aluminium scraps, as an example, the recycling and elution properties of the salt slags are discussed. Our research indicates that the viscosity of the salt flux is increased with addition of non-metallic components, that a certain percentage of fines remain in suspension, which determines the viscosity, affecting the settling of heavier materials. High slag viscosity will lead to more fine aluminium metal entrapped in the salt slag (may also be seen as a high temperature slurry), and thus increase the load of salt slag recycling. Keywords: recycling, environment, metallurgy, slags, fluxes, salts.

Jan 1, 2004

By S. Combrink, N. Naude

Hydrocyclones are widely used in wet mineral classification applications and can be notoriously prone to wear. The methods currently used for quantifying hydrocyclone wear profiles are mostly twodimensional. In this paper it was attempted to quantify and monitor wear in three-dimensions, using a micro-CT scanner (Nikon XTH 225 ST). Hydrocyclone wear and, more specifically, spigot wear was investigated on a Multotec HC250 (Dc 250 mm, barrel diameter) hydrocyclone. The hydrocyclone is lined by a vulcanised natural rubber compound within a metal shell, with a thermosetting polyurethane spigot and vortex finder. Tests were conducted on the hydrocyclone in a pilot-scale recirculating test setup. The wear rate of the spigot was quantified by measuring the volume change within the spigot over 122 days in operation, using the micro-CT scanner. After 122 days in operation (recirculating feed materials) the wear in the hydrocyclone led to only a 13.67% loss of spigot volume. The relatively low wear rate could be related to the fact that material recirculation led to particle smoothing and a reduction in size, thereby decreasing the wear rate. This also shows the enormous influence that particle shape and size have on wear. The research was conducted with the support of Multotec, NECSA and the University of Pretoria. Keywords: Wear, hydrocyclone, micro-CT

Jan 1, 2020

By J. L. Human, N. Fernandes

The rockfall hazard is the major contributing agency to fatal accidents in South African platinum mining operations. The majority of these accidents occur in close proximity to the working stope face. The collapse of fractured or blocky ground between individual temporary support units or the closest permanent support line to the stope face has not yet been adequately addressed. A large-scale stope support system testing facility funded by the Safety in Mines Research Advisory Committee (SIMRAC), has been designed and constructed to test support systems and stimulate innovative thinking by mining personnel, support manufacturers and suppliers by providing a facility where the interaction of stope support systems, a rigid stope face and a discontinuous hangingwall beam can be observed during quasi-static and dynamic conditions. Tests have been carried out on various types of stope support systems, focusing on the temporary support systems used in the immediate stope face area. The interlinking of the temporary support units with mesh or safety netting has been explored in the prevention of falls of ground between support units during gravity driven falls of ground. These tests illustrate the facility?s ability to be used to stimulate innovative thinking and provide a testing ground for the development of temporary support systems in order to reduce the risk off all of ground injury to mining personnel at the stope face.

Jan 1, 2004

By F. Shi , D. Lay, C. Antonio

High Voltage Pulse (HVP) technology has the potential to transform traditional mineral processing practice in the mining industry. HVP pre-treatment has been shown to enable ore preconcentration, achieve ore pre-weakening and improve mineral liberation. In order to improve the efficiencies of these novel HVP applications, it is essential to understand how HVP operational factors affect ore breakage in HVP pre-treatment. A two-level fractional factorial experiment using two rock samples, a gold-copper ore and a basalt sample, was performed to determine which factors have statistically significant influences on breakage probability, size reduction, and energy efficiency, and which factors have insignificant influences. Operational factors investigated include applied voltage, electrode gap, number of pulse discharges, the number of rocks being processed per batch, and rock size. In total, 1920 batch tests were conducted. For ore breakage characterised in terms of breakage probability and the degree of size reduction during HVP pre-treatment, the dominant factors were identified to be the number of pulse discharges, voltage, and the number of particles present in the processing zone. As all these three factors are related to the specific energy, it is concluded that the specific energy is the most important factor controlling ore breakage in HVP treatment. In terms of the efficiency by which spark energy is transferred from the generator energy, the factors found to have the most dominating influence were the particle size, the number of rock particles present in the processing zone and the voltage. Increasing the values of these factors reduced the loss of HVP energy during the energy transfer process. The factorial experiment using the two ore samples with vastly different mineralisation produced similar results. This proves that the dominant factors affecting HVP breakage are generally applicable to different ores types. Keywords: High voltage pulse, ore breakage, factorial experiment, specific energy

Jan 1, 2020

By A. Chryss, L. Pullum

Shear-thickening suspensions abound throughout the hydraulic conveying industry; at least this is the perception of many engineers running plants where hydraulic conveying is commonplace. In reality, shear thickening behaviour is limited, in the main, to high concentrations of fine particles, including colloidal and biological suspensions, at moderate to high shear rates. In the authors? experience most cases of shear-thickening behaviour have been either simple ?coarse? particle interactions, poor instrumentation techniques, or both. In some cases these were obviously heterogeneous flows, while in others flows that were homogenous, or were thought to be homogenous. Examples, which illustrate this erroneous perception are given. However, the trend towards pastes and complex suspensions that use high concentration carrier fluids means that the underlying slurries for many of these flows may now be truly shear-thickening. Unfortunately, suspensions that might exhibit shear thickening also invariably exhibit slip, or wall-particle depletion. These separate phenomena are difficult to resolve experimentally and many observations of apparent shear-thickening behaviour are in fact obscured or convoluted by slip effects. A method is presented whereby the true flow properties of these high concentration suspensions, and hence accurate prediction of pipeline flows, can be made using a parallel plate rheometer.

Jan 1, 2007

By M. Somerville, S. Sun

The liquidus temperature and viscosity of a range of melter slags produced in South Africa were determined. Drop-quench experiments were carried out on the supplied plant samples to determine the liquidus temperature and phase relations at sub-liquidus temperatures. The temperature measurement range covered 1300°C to 1630°C. Results from these experiments show liquidus temperatures for the melter slags to be in excess of 1500ºC with the chromium containing spinel as the primary crystalline phase. At lower temperatures, an olivine or pyroxene phase co-existed with the spinel phase. The viscosity of the slags was determined over a temperature range of 1350 to 1550°C, under a controlled atmosphere. Results show two orders of magnitude variation in the viscosity (0.2 to 20Pa s) with strong effects of slag chemistry and temperature. Slags with lower SiO2and Cr2O3concentrations were more fluid. Slags with the lowest FeOx and highest SiO2concentrations were the most viscous. These observations are in accord with general behaviour of silicate slags. While the presence of a spinel phase may have an effect on the viscosity of the melter slags, results obtained to date indicate a much stronger effect due to the presence of an olivine or pyroxene phase at lower temperatures. Keywords: phase equilibria, liquidus, viscosity, slags, olivine, spinel, pyroxene

Jan 1, 2004

By D. F. Malan, J. A. L. Napier

A number of shallow coal or hard rock mines employ pillar mining systems as a strategy for roof failure control. In certain platinum mine layouts, pillars are designed to ‘crush’ in a stable manner as they become loaded in the panel back area. The correct sizing of pillars demands some knowledge of the pillar strength and the overall layout stress distribution. It is particularly important to understand the impact of the layout geometry on the effective regional ‘stiffness’ of the rock mass around each pillar. An important design strategy is to model relatively detailed layout configurations which include a precise representation of the local pillar layout geometry and to analyse multiple mining scenarios and extraction sequences to select optimal pillar sizes and barrier pillar spacing. Although computational solution techniques are now impressive in terms of run time efficiency, a major difficulty is often encountered in assigning suitable material properties to the pillars and in devising an effective material description of the layered rock strata overlying the mine excavations. This paper outlines an efficient numerical strategy that can be used to assess large-scale pillar layout performance while retaining the ability to modify individual pillar constitutive behaviour. The proposed method is applied to selected layouts to compare estimated average pillar stress values against values determined by detailed modelling and against observed behaviour.

May 3, 2023

By R. Gurung, S. Asokan, Ch. V. G. K. Murty, R. Upadhyay

Tata Steel Limited which is Asia?s first and India?s largest integrated private sector steel company, as part of its vision to grow in related industries is also undertaking the Titania project. The project will involve mining, separation of ilmenite and other valuable minerals from the inland heavy mineral sands deposit in the Indian state of Tamil Nadu. The raw material will be beneficiated to synthetic rutile, titanium dioxide pigment and ultimately to titanium metal. The recently concluded feasibility study revealed that the deposit under consideration has 10.4%of total heavy mineral content and 15.2% slimes of the size below 63 µm, over an average sand thickness of 6.9 metres. The presence of about 15% slimes in ROM sand coupled with scarcity of water at the project site complicates the slimes handling/disposal system, requiring the development of an innovative, efficient and effective system for disposal of slimes. Mineral characteristics of slimes revealed the presence of kaolinite clay, which poses its own challenges in thickening/dewatering of slimes. This paper outlines the detailed studies conducted, including slime characterization, settling and thickening characteristics, and ge-technical studies to arrive at an efficient and effective slime handling/disposal system, with a view to plant saplings on the mined-out reclaimed land with species typically suitable to that environment.

Jan 1, 2007

By S. Poirier, J. -M. Facteau

The gold mine sector is presently facing low gold prices as well as technological challenges. Its competitiveness and survival will depend on new mining methods and equipment to improve ore extraction. In 1999, Natural Resources Canada has invested new funds over a period of three years at CANMET’s Experimental Mine to establish the Narrow-Vein Mining Project. A team of engineers and researchers specialized in mining, mechanics and electronics engineering are working to meet the critical need of ore-extraction technology. CANMET’s programme in mechanization and automation for narrow-vein mining had, prior to 1999, realised several important achievements, many in co-operation with a consortium of mining companies(Soredem). The investment of new funds in this area will contribute to develop technologies to improve the productivity, as well as health and safety conditions of the narrow-vein mining industry. Several important impacts of this project will be monitored. In particular, a database of methods and equipment used in narrow-vein mining is being developed. A key thrust is to identify operators’ needs with respect to the development and automation of mining methods and equipment. Based on those needs, research and development projects will be created. The paper will present the objectives of the narrow-vein mining project and some of the results, including the web site developed to present the results of the project.

Sep 1, 2001

Most processing plants use automatic samplers to extract ore aliquots along a producing shift. These aliquots are combined into a sample normally sent to lab analysis. The sampler used in the extraction of an aliquot from a continuous flow of ore, i.e. a belt conveyor is required to be both precise and accurate. Surprisingly, not all commercial automatic samplers exhibit these two mandatory properties. Consequently, it is recommended the development of a procedure able to check sample assays reproducibility obtained using a given sampling protocol. This paper uses the Gy’s sampling theory to evaluate coal quality control practices at a washing plant using an automatic sampler extracting coal increments from the ROM feeding belt conveyor. Gy’s theory provides the means to establish the precision limits for a given sampling protocol. Various ore properties are required to be determined in combination with sample mass and mass of the lot sampled. All this information leads to the definition of the precision limit. The precision limit obtained was checked via an experiment mimicking what happens in situations where both miner and consumer use the same and appropriate sampling practices. The experiment demonstrates that sampling theory precision limits were valid if unbiased samplers are used by both parties, i.e. miner and consumer. Keywords: sampling, quality control, coal

Jan 1, 2003

By H. Ramazi, A. Amini

"This article is devoted to the introduction of a new technique of electrical resistivity data processing called residual resistivity (RR). We define RR as measured resistivity minus background resistivity. To determine the background resistivity, the data acquired from electrical resistivity measurements along a given survey line is evaluated, and then an equation is fitted to the data corresponding to a chosen measurement station as a function of current electrode spacing (or array length). The RR technique was applied to several synthetic models to compare the conventional resistivity inversion of each model with its RR-based inversion. A case study was carried out in a karstic area in Zarrinabad, Lorestan Province, western Iran, to detect the location and geometry of probable cavities by conventional resistivity inversion and RR-based inversion. The results showed that the anomalous zones are better highlighted in the RR-based inversion images in comparison with the conventional inversion images. In some cases, anomalies detected by the RR-based images were hidden in the conventional method. IntroductionThe geoelectrical resistivity method has been widely used since the early 20th century, and plays an important role in several fields such as groundwater and subsurface mineral exploration, geotechnical and environmental investigations, and archeological studies (Bayrak and Senel, 2012; Candansayar and Basokur, 2001; Fehdi et al., 2011; Hee et al., 2010; Osella et al., 2003; Wilkinson et al., 2010). The goal of geoelectrical resistivity surveys is to determine the distribution of subsurface resistivity by measuring the current-potential difference on the ground surface (Aizebeokhai et al., 2010). In the electrical resistivity method, an electrical current is injected into the ground by two electrodes, called current electrodes (AB), and the potential difference is measured between another pair of electrodes, the potential electrodes (MN). Several methods of interpretation are available for application to electrical resistivity data, the simplest being the graphical interpretation of the apparent electrical resistivity pseudo-sections along each survey line. A second method, electrical resistivity inversion, has been developed to create relatively accurate two- and threedimensional computational resistivity models of subsurface sections (Loke and Barker, 1996; Niwas and Mehrotra, 1997; Nordiana et al., 2014; Oldenburg and Li, 1994; Papadopoulos et al., 2009; Yilmaz and Narman, 2014). In the inversion method, models of subsurface objectives are mathematically inverted to reach optimal solutions subject to prescribed objective functions, constrains, and convergence criteria. A common problem when using the electrical resistivity inversion method is that the inversion model of an electrical resistivity profile may be non-unique because different inhomogeneities in the investigation media can result in the same electrical response (Smith and Vozzof, 1984)."

Jan 1, 2016

By L. Raaths

This paper outlines the process of improvement utilizing performance monitors and GPS systems on an opencast strip mine. Its primary focus is to maximize coal exposure by draglines and secondly to improve on those processes impacting directly on the dragline operation. The Aquila (DM2/5 system) navigation and monitoring systems were installed on the overburden drills. Their main function is to eliminate manual staking and positioning thereby ensuring a regular pattern being drilled. Holes drilled to planned depth reduce drill metres and it minimizes coal losses and contamination at the coal interfaces. The CAES (Computer Aided Electronic System) will be installed and evaluated on the Caterpillar D11 dozers at Optimum. This system ensures a correct dragline pad elevation through the use of planned elevations and GPS technology to achieve the optimal pad elevations for draglines consistently. The draglines are equipped with a Dragline & Operators Performance Monitor. This monitor allows the operator to control his own performance. It reports on all productivity, method and poor operating techniques. These monitoring systems send critical operational information back to the office. This source data resides in central databases from where it is converted and integrated into management information. To manage an operation means that you as a manager must be able to set objectives and targets and to achieve your goals the activities involved must be measurable.

Sep 1, 2001

By C. Debek, A. Wasilewicz, T. Czysz

"Both Polish and European hard coal mining nowadays faces the need of deepening shafts (significantly in some cases) or extending mining hoists, due to the exploitation of deeper coal deposits.In order to protect the crew working within a shaft, rope safety platforms (artificial shaft bottoms) are employed. Old solutions, based on rigid steel constructions with the external damping layers made of e.g. slag and up to several tens of metres long, are intended to absorb the energy of approximately 5 t mass falling a distance of 700 m. However, current requirements often assume a drop of 20 t to a depth of 1000 m or even more.More modern safety platform structures, made of one or more support rings with steel ropes stretched on them (rope platforms), are more compact (up to 3 m high) and lighter than traditional solutions. Multi-ring rope platforms with additional damping layers filling the empty spaces between the ropes are able to absorb sufficient energy to meet the current requirements.Single- and double-ring platforms have been employed in Poland to absorb the energy of approximately 5 t dropping to a depth of 900 m. They have been developed (and some have already been implemented) by SADEX Ltd. and are protected by various patents and patent applications.This paper presents a design for a triple-ring platform structure with six rope nets. FEM analysis was used to model the performance of the platform. According to the simulation, a 20 t mass falling from 1000 m (>100 m/s) will destroy all the nets, breaking most of the ropes and deforming the support steel boards placed on the nets, but will ultimately be stopped by the platform, as its kinetic energy falls to zero."

Jan 1, 2017

By D. Hanekom

Over the past couple of years, Anglo Platinum has made extensive use of technology within the core disciplines (geology, evaluation, survey, and planning) that collectively form part of mineral resource management (MRM). While these technologies were primarily developed to enable geology, evaluation, survey, and planning to carry out their daily tasks, with the main objective of supporting the mine?s production effort, they have also enhanced the disciplines? ability to produce the required outputs within the annual business planning cycle. Anglo Platinum has developed a very comprehensive business planning process, and these technologies play a vital role in enabling both the quality and quantity of inputs into the process, and also the value-add of the final product. This prompted a question regarding the practical application of the CADSMine software. If we changed our thinking in how we applied the software, would it be possible to further improve on the time taken to deliver a business plan? In changing the current planning approach, would we be able to further simplify the process? Is there a way to reduce the data generated in order to enhance the time taken to do reporting, as the CADSMine software is totally network dependent? Less data should equal faster reporting. This paper focuses on the practical application of the CADSMine software, and demonstrates the value-add to the business planning process that can be gained if the mine design methodology is changed from individual panels to bigger blocks representing a raise line.

Jan 1, 2012

By J. Hadjigeorgiou, G. Knox

There is a considerable wealth of information on the behaviour of rockbolts under axial loading conditions both in situ and under controlled laboratory conditions. However, there is comparably less data on the behaviour of rockbolts in shear. Several authors have contributed to the understanding of the behaviour of conventional rockbolts’ performance under shear loading. Much of this data have been gathered through experimental programmes conducted on sections of the rockbolt. Considering the continuous coupling between the rockbolt and borehole interface, the approach is justified. Due to the design premise of energy-absorbing rockbolts with discrete couplings, full scale testing is required to quantify the behaviour of the rockbolts. This paper reviews published results obtained from two testing facilities, which are the SINTEF rockbolt pull test rig in Trondheim, Norway and the Epiroc Combinations Shear and Tensile test rig in Johannesburg, South Africa, both capable of conducting full scale testing of rockbolts. Based on this high-quality database it was possible to identify three distinct responses of rockbolts in shear. The behaviour under load is controlled by the presence or absence of an encapsulation medium (resin/cement grout), the reinforcement mechanism, and whether the rockbolt is continuously or discretely captured. As a reference the results are compared to the performance in shear of conventional grouted rockbolts.

Nov 24, 2025

By Y. Fan, D. H. Zhang, J. Y. Xu

The hydrogeological conditions in the Chambishi mine area in Zambia. were investigated. Chambishi is a very wet mine and groundwater discharge costs are high. The research goal was to identify methods to reduce the discharge costs without greatly affecting the mining process. Hydrogeological data was obtained from measurements in drill-holes and from drill cores. The differences in structural deformation in different areas determine whether a layer of rock is an aquifer. In the mine region, the Lower Roan Group ore shale and quartz-sandstone unconformably lie on the basal schist and granite aquifuge. The Upper Roan Group dolomite is continuously distributed over a large area around the orebody. This dolomite is the main target of groundwater control efforts, and its water yield is also influenced by the deformation intensity. Based on the observations, backfilling was gradually adopted to appropriately safeguard the integrity of the aquifuge above the orebody. The overlapping relationship between the aquifer and aquifuge has been utilized to increase mine drainage efficiency. This measure has not only greatly reduced the costs of mine drainage, but also improced protection of the groundwater environment. The old drill-holes that were not sealed after exploration drilling were grouted. Further, possible water-conducting fracture zones were investigated. Cover drilling towards the suspected zone was conducted to prevent the high-pressure groundwater from shallower aquifers from entering stopes in deep areas of the mine.

Jun 10, 2024

By S. Subramanian, L. Mweene

A siliceous low-grade copper ore from Mpanda Mineral Field (MMF), located in south west Tanzania consisting of SiO2 (58.3%), Fe (10.4 %) and Cu (0.9 %) was initially subjected to selective dispersion-flocculation using sodium trisilicate (STS) as a dispersant and xanthan gum (XG) as a flocculant. Subsequently, the selectively flocculated fraction was floated using a collector combination of potassium ethyl and amyl xanthate (1:1) in the presence of poly-ethylene oxide (PEO) as a silica depressant, to get a copper concentrate. The mineralogical investigations confirmed that the MMF ore was mainly composed of quartz, chalcopyrite and pyrite. Adsorption studies indicated that the adsorption density of XG on MMF ore decreased with an increase in pH, while that of PEO was independent of pH. The adsorption isotherms of XG and PEO on MMF ore exhibited Langmuirian behaviour. The zeta potential studies of MMF ore indicated that the iso-electric point (IEP) was located at pH 2.6, presumably due to its high silica content. In the combined presence of XG and STS, the zeta potential of MMF ore became more negative, with an increase in the concentration of STS. However, in the presence of PEO, the zeta potential of MMF ore became less negative with an increase in the concentration of PEO beyond the IEP, without shifting the IEP. Selective dispersion-flocculation of MMF ore improved the flocculated chalcopyrite grade to 19.8 %, yielding a degree of flocculation and a maximum separation efficiency of 12.1 % and 85.7 % respectively, after three desliming stages in the presence of 30 ppm of STS and 30 ppm of XG. A copper concentrate of 29 % grade and 90 % recovery containing silica of 0.9 % grade and 1.7 % recovery was achieved by flotation of the selectively flocculated component, using PEO as a depressant for quartz. Keywords: Flotation kinetics, flotation machines, flotation bubbles, particle size

Jan 1, 2020

By J. Petersen, H. Naderi, H. Zare, M. H. Nikzad, M. Karimi

In the copper electrorefining process, the dissolution of anodes is significantly reduced or even stopped when the passivation phenomenon occurs. The results of this phenomenon are increasing energy consumption, residual formatting, and voltage levels in the cell. In this study, the electrochemical behaviour of blister copper in the presence of sodium persulfate (PDS) was studied. The electrochemical methods of LPR, Tafel, and Electrochemical Impedance Spectroscopy (EIS) were used. The results showed that the addition of sodium persulfate activates the electrode surface and increases the open circuit potential. In the presence of PDS, the polarisation resistance of the electrode shows an increasing or decreasing tendency, based on the PDS concentration. This tendency is probably due to the formation of surface layers (such as slime layer or copper sulfate) and dissolution of this layer at various concentrations of PDS. The lowest polarisation resistance of 1.8 ohms and the highest corrosion current of 60.6×10-3 and 36.6×10-3 A/cm2 from LPR and Tafel techniques respectively were obtained at the concentration of 40 g/l PDS. Based on the results of potentiodynamic and electrochemical impedance spectroscopy tests, the addition of sodium persulfate to the solution reduces the corrosion resistance, therefore the passivation time of the blister copper anode increases. Keywords: Blister copper, electrorefining, sodium persulfate, anodic passivation

Jan 1, 2020

By P. L. Moolman

An approach to the design of a tailings disposal system is presented using an example from a platinum project on the eastern limb of the Bushveld Complex as a base case. The design is driven by two inputs: namely, maximizing water recovery and minimizing power cost, expressed as cubic metres and kilowatts per ton of solids deposited on the tailings storage facility respectively. The approach considers low-, medium-, and high-density platinum tailings and uses material-specific aspects such as thickening and rheology to determine the most economical option. An analysis based on direct capital and operating cost (water and electricity) shows that the medium-density scenario results in the lowest total cost per ton of tailings deposited, even though this system results in the highest electricity consumption per ton of tailings deposited. As the cost of water and electricity is likely to increase in the future, the higher-density tailings disposal options become more economical, with the paste option the preferred option.

Jan 1, 2012

By O. O. Ogunmodimu, D. K. Weatherley, M. S. Powell

Discrete element methods (DEM) have provided the ability to resolve the complex phenomena experienced by ore within comminution devices such as tumbling mills. The new developments in DEM techniques and the corresponding increase in computational power have made it more feasible to study the movement of individual ore particles as they traverse a tumbling mill. A range of information can be extracted on individual particle impact histories, such as kinetic energy at the time of collision, velocities of individual particles, per-particle stress tensors, impulse, and collision energy. DEM codes have been modified to provide required information that can be analysed in associated software to investigate the impact of varied operational parameters on the resultant granular dynamics. This paper explores the reaction of individual ore particles to the breakage environment within a tumbling mill using DEM techniques and studies the stressing conditions that would lead to either impact or abrasive breakage. Keywords: DEM, comminution, tumbling mill, breakage

Jan 1, 2020