Search Documents

By M. Morales, J. Yianatos

"In this work, an alternative approach to evaluate the flotation performance along a flotation rougher row is presented. The collection zone as well as the froth zone performances were separately evaluated. For this purpose, sampling for metallurgical balances along with sampling of top-of-froth (TOF) grades in each cell of a flotation row were employed. The modelling of the rougher circuit consisted of using TOF grades for evaluating the collection zone recovery, because they are a good representation of the bubble loading, which identifies the true flotation process, as shown in previous studies for shallow froths. In addition, the feed characterization, size-by-liberation, allowed the identification of the mineral distribution and its evolution along the circuit. The latter result was obtained by fitting the recovery profiles as well as the TOF grades down the flotation bank. The flotation rates and the maximum recoveries in terms of size-by-liberation (size classes: -45 µm, +45-150 µm, +150 µm, and liberation classes: -20%, +20%-80%, +80%) were then estimated. The results were in good agreement with those reported in literature by other authors and showed the new approach allows flotation kinetics to be characterized in industrial circuits.INTRODUCTIONMineral recovery in industrial flotation circuits is a function of the mineral characteristics, such as particle size distribution and liberation (Trahar, 1981, Jameson, 2012), and operating conditions such as air flowrate, pulp flowrate, solids percent and reagent conditioning (Jameson 1977; Klimpel, 1980; Mehrotra and Kapur, 1974). The cell type and size (self-aerated or forced air) and the circuit arrangement (single cells or banks of cells in series) are also relevant factors. Sampling of circuits (e.g. rougher, cleaner or scavenger) are commonly carried out using standard automatic samplers for metallurgical balance assessment. However, the flotation plants are generally not provided with proper accesses for local streams, which hinders the recovery estimations and the flotation rate characterization."

Jan 1, 2018

By Xiaoxu Sun, Jianchao Yao, Jiancheng He, Shijie Lu, Hongxi Zhou

"With the trend of increasingly more mineral resources turning low-grade and refractory, more and more new ore bodies being developed worldwide are more finely grained, which drives the rapidly development and application of techniques related to tower mills (vertical spiral stirred mills). However, the lacking in fundamentals of fine grinding, as well as standard procedures for equipment selection and scale up, seriously restraint high efficient application of tower mills. Taking grinding media motion characteristic and grinding intensity as a breakthrough point, this paper studies mechanisms behind how critical parameters affect grinding efficiency of tower mill, including ratio of screw pitch and diameter, agitator rotation speed, grinding media size. Several sets of orthogonal test are conducted on the quartz ore using the grinding system of KLM-3 tower mill. All the tests are under the same character of feeding mineral and undergo the consistent sampling for at least 60min grinding time. The input power is measured by a torque measurement system and the grinding products are analyzed by the laser particle size analyzer. The test results show the influence of parameters on grinding efficiency. Among the three important parameters, the effect of grinding media diameter is the biggest, followed by the agitator tip speed, and finally the ratio of screw pitch and diameter. For the different particle size of grinding products, the best combination of grinding parameters is different, with the mineral size becoming finer, the ratio of screw pitch and diameter become smaller, the diameter of grinding media become smaller, while the agitator tip speed does not change too much. The conclusions of the study help us to improve the grinding efficiency of the tower mill, to assist in the selection and optimization of working parameters, establish new scale up method on the basis of grinding model and eventually provide theoretical basis of rational selections of structural and media physical parameters within tower mill."

Jan 1, 2018

By K. W. Major

"This chapter outlines the organization of mine/ mill complexes in Canadian mining companies. Many factors unique to the Canadian mining industry will affect the design of the organization in the future: geographic location, the size and the type of orebody, etc. Mining companies cannot choose where new operations will be located, that is dictated by the location of the orebody. New mines are seldom started near established communities. Rather, the towns usually grow up near the mines. The remoteness of most Canadian mining operations has caused severe problems in attracting and/ or retaining all levels of employees. This means that training has a high priority within each operation.Another factor affecting mine/ mill organizations is the size of the operation. Larger operations generally require more departments and increased specialization to manage equipment and manpower effectively. Thus, for mine/mill complexes, organizational charts are less standardized than in other industries. It is often necessary to organize around the work force rather than develop a chart and then acquire the trained personnel to fill the diagrammed positions.The information presented in this chapter has been derived from the responses received from a survey of Canadian mining operations.Principles of OrganizationOrganization can be defined as deployment of personnel to accomplish definite goals. In the mining industry, the major goals are typically the projected number of tons and grade of ore mined on a daily, weekly, monthly and yearly basis. Organizing involves establishment of authority relationships with provisions for both vertical and horizontal co-ordination within the company structure. Vertical co-ordination is the delegation of responsibility and communication of goals and reporting of progress between the supervisor and subordinate. Horizontal co-ordination is communication between departments at positions of equal authority to determine methods of achieving predefined goals. The organization structure must reflect the objectives and plans of the company, and must clearly define areas of authority.Two criteria for effective organization are departmentalization and manpower planning."

Jan 1, 1989

By Corrie Pitzer

Safety performance in many companies and even industries has stalled in the last decade. Accidents rates are improving but more slowly and yet, serious accidents and fatality rates are not: in fact, these rates of more serious incidents have plateaued or deteriorating. In more dramatic cases, organizations that had ?exemplary? safety statistics, suddenly had a catastrophic or multi-fatality event occurring. Popular books such as In Search of Excellence of Peters and Waterman or Good to Great of Jim Collins created many delusional ?secrets? or recipes, to achieve great performance and yet, most of those ?great? or ?excellent? companies have now declined in their performance, some dramatically and some have fallen from grace, like Fanny Mae, a company Jim Collins identified as a ?great? one, that had to be bailed out in the latest financial crisis. These organizations share several ?delusions? about managing a business, and often, these delusions are created by academics, consultants and authors of popular books about (safety) management. More damaging however is that safety management is defined by a set of key practices or axioms: a focus on human error, compliance to rules and regulations, creating consistency of systems and actions, reacting to accidents and incidents and on prevention of those, measuring safety with performance metrics and rewarding employees on those measurements. All of these axioms contain the seeds of destruction, and they create conditions and dynamics that precede the disaster - and ironically, they are all 'good things' we do in safety management. For example, a mere focus on safety in the business, and the measurement of it, create a culture of repression of mistakes and incidents, leading to a situation where the organization knows incrementally less and less of risks and risktaking behaviour - until the day it all coincides destructively! This paper discusses seven such safety delusions and how they impact on the views and safety management approaches. They are: ??The delusion of (risk) control, that risks can actually be identified, analyzed and mitigated. ??The delusion of compliance, that mere compliance to rules will safeguard the business ??The delusion of consistency, that standard operating procedures will ensure safe operations ??The delusion of predictability, that accidents and trends tell us everything about the risks of the future ??The delusion of human error, that people are the weakest link and that it can actually be dealt with through discipline and enforcement. ??The delusion of statistical trends, that safety is measurable with statistics ??The delusion of invulnerability, that we have achieved high levels integrity and capability to deal wit risks. Organizations that suffered catastrophes all share some or all of these delusions and this paper traces how these played a role in many disasters, ranging from the Titanic, Challenger, Piper Alpha, Bhopal, BP Deepwater Horizon and many more.

Aug 1, 2013

By W. Bassow

In June 1972, when the United Nations convened its historic Conference on the Human Environment, only 24 countries had established government agencies with environmental responsibilities. Of these, 11 were in the industrialized world, 13 in the Third World. By 1985, the number had dramatically surged to a world-wide total of 145, with the greatest growth among the developing countries to 110, an increase of almost 1000%.

Jan 1, 1988

By Arkady Senchenko

The application of centrifugal separation methods with the use of gravity concentrators has been assigned high priority while gold-containing minerals processing. The separation proceeds under centrifugal force resulted from the rotor spinning and wash water flow in the concentrators. The high specific gravity particles are retained at the trapping surface of the cone, and the low specific gravity particles are brought in the tailings. The centrifugal field in such concentrators (Knelson, Falcon) is generated by the rotating cone provoking the swirling of the free fed slurry flow. The author investigated the regularities of the separation process in the centrifugal gravity concentrator where a two-phase flow of the separated mineral media is under the pulsed pressure of the fluidization water and air. As a result of the study the possibility of the deeper penetration of the fine heavy fraction into the cone rings, providing the fluctuation of the fluidization water or air flow, was theoretically argued and experimentally proved. This allows the increase of the separation performance at low pulsation costs. The developed mathematical models are in close conformity with the actual process of interest and they enable the prediction of the heavy phase behavior at the isolated process stages in the concentrator. Keywords: gold, centrifugal gravity concentrator, containing, specific gravity, cone ring, pulsation, cost, fluidization water, Knelson centrifugal separator

Sep 1, 2012

By Aníbal Gastanaga Coll

El texto refiere cuáles son los límites de tolerancia a concentraciones máximas permisibles para polvos industriales capaces de producir silicosis. Estos límites fueron establecidos por primera vez en 1947 por la Conferencia Americana de Higienistas Industriales del Gobierno de Estados Unidos, la cual fue modificada en 1962. También se describe una breve reseña sobre la evolución del concepto de limites permisibles, referidos al contaminante del polvo y se determina algunos aspectos sobre la ecuación para el cálculo de dichos límites, aplicable en polvos que contienen sílice libre en su forma cristalizada.

Aug 20, 1963

By Hans Langerfeldt

La explotación minera se limita al marco geológico de una zona -en tanto se evalúen las características geológicas y mineralógicas de la zona a explotar-. En este sentido, el texto describe el volumen y ley, topografía, geología, extracción, metalurgia, agua como elementos necesarios para proceder a utilizar el método de explotación y de tratamiento. Sobre la base de estos factores se evalúa el planeamiento técnico de la explotación de Cerro Verde.

Nov 20, 1969

By Steve Kral

The Underground Construction Association?s (UCA) 2014 North American Tunneling (NAT) conference is expected to attract about 1,000 tunneling and underground construction professionals. With the theme ?Mission Possible,? attendees from around the world will hear the latest in tunneling and underground construction technology in the two-and-a-half days of technical sessions. The meeting is scheduled for June 24-27 at the JW Marriott Los Angeles Live in Los Angeles, CA. In addition to the technical programming, the accompanying exhibit has attracted 143 exhibitors in 162 booths. And the conference will offer short courses and plenty of social activities that will provide attendees the opportunity to catch up with each other. In addition, a proceedings volume containing all of the 128 papers will be available. An impressive lineup of sponsors will help attendees enjoy the conference. They include Brierley Associates, Kiewit Infrastructure Group, Parsons, Skanska, Traylor Bros., MWH and HNTB.

By G R. Hancock, J F. Martín Duque

Post-mining landscapes are required to geomorphologically and ecologically integrate with their surrounds (Martín Duque et al., 2015). Designing and constructing an erosionally stable landform is the first and arguably most important part of the rehabilitation process. Without an erosionally stable landform topsoil and nutrients are lost, shallow groundwater is depleted as well as when excessive erosion occurs, expose suboptimal materials. Here we examine the ideas of geomorphic design and rehabilitation and how the landform can be tested and enhanced using computer based design and landscape evolution models. Specifically we evaluate the complementary capabilities of landscape modelling (SIBERIA) (Hancock and Willgoose, 2017) and geomorphic design software (Natural Regrade with GeoFluv) (Bugosh et al., 2016), in order to maximise erosional stability on post-mining landscapes (Zapico et al., 2018). CITATION:Hancock, G R and Martín Duque, J F, 2018. Geomorphic design and landscape evolution modelling for best practice mine rehabilitation, in Proceedings Life-of-Mine 2018, pp 119–121 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By Mike Preston

Attrition scrubbers may not be glamorous, but they are an important and sometimes neglected step in mineral processing. Optimal attritioning will significantly improve the results and efficiencies of subsequent processing steps and can lead to reduced costs and improved product yields. Why is attrition scrubbing used? Attrition means to wear away a surface, typically by friction or abrasion. An attrition scrubber does exactly this, using impellers to force particles against each other, causing intense scrubbing, grinding, abrasion and polishing. This process is not a new concept. It has long been used in the glass industry to remove surface contaminants from silica. But it is also widely used in many areas of mineral processing and other applications including soil remediation and plastics recycling. In mineral separation, for example, the scrubbers help improve yield and efficiencies by preparing feed materials for downstream processes such as flotation, magnetic or electrostatic separation. Inefficient scrubbing can lead to coatings remaining on valuable minerals and decreased yields, as the covered minerals cannot be processed efficiently or are mistaken as waste contaminates and removed. In the example of flotation separation, pre-flotation conditioning uses attrition scrubbers to provide better recovery of minerals while using fewer chemicals. If surface contaminants remain on the mineral, yield is reduced, as the unwanted coating acts as a barrier to the reactants, which make it unfloatable and, therefore, unrecoverable.

Oct 1, 2013

By George L. Wilhelm

Many factors, some of which are not easily defined or described, must be considered in the design of a hydraulic backfill system. After participating in the design of several plants, I have a conviction that future refinements in sandfill systems must come in large part, from the merging of good design ideas and information from existing operating plants. It is important then, that we document and publish information on existing plant designs and their operating characteristics. This information will then be available for use by our successors and later innovators in hydraulic fill placement. The Mayflower hydraulic sandfill system is similar to other plants. The intent of this paper is to describe only this system's unique design and operating characteristics. I will not describe in any detail, the familiar elements of the system. I will document some of the observed hydraulic characteristics of the system, elaborate on some of the design situations that had to be solved, and will discuss operating factors that are not generally described in our technical literature.

Jan 1, 1968

By Pratt Rogers, Aaron Young

This paper considers the mining industry’s need for digital transformation (DT) and presents a three-part review of the foundational components of the DT process: ubiquitous data, connectivity and decision-making. It also provides a discussion on the future of DT in mining as well as a research direction, which identifies the need of academia to provide support for mining companies in the form of both research and the education of digitally literate, dynamically capable mining engineers into the coming decades.

By Andrea Brickey, JUDITH BUABA, RICHARD AMOAKO

This study applies a machine-learning technique known as multiclass logistic regression on a 10-year injury dataset from the U.S. Mine Safety and Health Administration (MSHA) to determine miners’ susceptibility to injury and to help identify significant risk factors associated with different classes of injury. The analysis identifies specific risk factors that influence a mineworker’s susceptibility to a given class of injury: nonfatal with no days lost or restricted activity; nonfatal with days lost and/or days of restricted work activity; and fatal and total permanent or partial permanent disability. These factors include miner’s age, mine type (coal versus noncoal), experience on the current job (years), shift start time, employment type (operator versus contractor), mining district and type of accident. The results of the analysis indicate that a miner’s experience on the job (the number of years worked in a current job) is a significant risk to injury occurrence, even for those with decades of total mining experience.

By MANZOOR ALI BROHI, IZHAR MITHAL JISKANI, Atta Ur Rehman, SHUAI HAN, MUHAMMAD TARIQ, NIAZ MUHAMMAD SHAHANI

The analysis of mine safety indicators using a scientific method can improve mine safety and assist management in making informed decisions. This research establishes a mine safety evaluation index and proposes an integrative evaluation model based on the entropy weight and grey clustering methods. The index consists of 27 indicators classified into seven criteria: working environment (A), miners’ attributes (B), safety policies and education (E), prevention and control (F), and monitoring and supervision system (G). Using Pakistan’s mine safety situation as a case study, the proposed model categorized the indicators into five safety levels (very low, low, medium, high, very high) for the present situation and for their relevance in terms of future safety improvement. The results show all of the criteria falling into the very low level for the current mine safety situation. Three of the criteria — C, E and G — are identified as having very high levels of significance for future safety improvements.

By M Rafty, C Lane

Managing water is a key aspect of mining, whether a site is in water surplus or water deficit. Water in tailings storage facilities (TSFs) needs to be managed carefully to maximise the density of the solids, maximise the re-use of available water and to minimise the risk of water overtopping the spillway in the event of heavy rainfall. Developing a water balance models is a standard method for monitoring the major flows of water around a site. However, models created by specialist consultants are often overly complex and are not suited to being used by process plant personnel after they have been handed over to the mine operator. Models typically offer information on water management at the time that they are created, but then ‘sit on the shelf’ and offer no further insight or value for operating mines. Advisian has developed a customised water balance model for a mine in Sub-Saharan Africa, which can be adapted to other locations, to assist in managing water at the site and in particular to predict the current and future water level and volume in the TSF under various rainfall scenarios. The model was developed using Microsoft Excel and requires no specialist skills to operate. Site personnel enter in daily production, water transfer and rainfall data and then view the output dashboards to observe the current water level and volume, decant rates, licensed water abstraction and water supply versus demand. The output dashboards were developed in close consultation with the client to ensure that all of the relevant key performance indicators were included, from the perspectives of all the key stakeholders. This modelling approach focusses on the needs of the people who will actually use the model to actively manage TSFs with the need to involve the model developer as part of ongoing operations eliminated. The simplicity of this approach is now being embraced by other mine sites in Africa and Australia. CITATION:Rafty, M and Lane, C, 2018. Water balance management 101, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 485–490 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By M. R. J. Wyllie, Michael A. Torcaso

With the continued deep drilling of today, increasing numbers of high pressure and high temperature gas-condensate reservoirs are being discovered. Correspondingly, the ranges of properties of gas-condensate reservoir fluids are also being increased. The literature1*'." contains several excellent reviews of the property ranges in presently known condensate reservoirs. When one examines these property ranges, it becomes apparent that the need for reliable data is great if the engineer is to evaluate properly or appraise a gas-condensate reservoir. It is the purpose of this paper to present phase-behavior data that will point out some of the important variables that influence recovery from gas-condensate reservoirs produced by pressure depletion. All these variables may be resolved into two major categories: the hydroc:arbon composition of the reservoir fluid and the physical properties of the reservoir. But the variables which we will consider are those which are usually determined from well tests shortly after discovery and are, consequently, readily available to the engineer. They are as follows: (1) the producing separator gas-stock-tank liquid ratio, (2) stock-tank liquid gravity, and (3) reservoir temperature. Laboratory depletion studies have been performed on several reservoir fluids to illustrate the effect of changes in the cronsidered variables upon ultimate recoveries. The deviation factors, Z, of a series of reservoir fluids were determined experimentally to illustrate their order of magnitude and their effect upon the calculation of in-place reserves existing at high pressurcs and temperatures. The procedures followed in conjunction with the performance of these studies and their associated calculations are illustrated in Fig. 1. For the purpose of this paper, the depletion recoveries are expressed only in terms of pcr cent of initial stock-tank liquid, with the abandonment pressure assumed to be 500 psig. VARIATION OF RECOVERY WITH INITIAL PRODUCING SEPARATOR GAS-STOCK-TANK LIQUID RATIO The producing separator gas-stock-tank liquid ratio has long been one of the principal criteria in assumptions and generalized correlations' used for the estimation of ultimate recovery from gas-condensate reservoirs. Fig. 2 presents a plot of the cumulative recovery of stock-tank liquid at abandonment as a function of the initial producing separator gas-stock-tank liquid ratio. The graphical illustration represents the results of 44 laboratory depletion studies performed on actual gas-condensate fluids. These data are presented not only to illustrate the general trend of ultimate recovery increase with initial producing ratio increase but to emphasize the considerable variation in possible recovery at any given producing ratio. Table 1 presents the properties of two actual reservoir fluids chosen to illustrate the approximate extremities of producing ratios for gas-condensate systems. The fluids designated as A and B exhibited initial producing ratios of 3,400 and 114,000 scf/bbl, respectively. Fig. 3 presents a graphical comparison of the cumulative stock-tank liquid recoveries, calculated from the well-stream compositions and produced volumes for each fluid during depletion. It is to be noted that Fluid A exhibited a recovery of only 16.5 per cent when produced to an assumed abandonment pressure of 500 psig while the corresponding recovery for Fluid B was calculated to be 62.2 per cent. This difference in recovery, which exemplifies the general trend of recovery increase with initial producing ratio increase, is readily explained by consid-

By Ignazio Carbone

"During the design of a typical modern subway, engineering aspects prevail since underground structures remain hidden to most humans. Aligning the advanced architectural concepts with the engineering requirements of the Naples Metro Line 1 (Italy) called for a thorough rethinking of the design process so that the engineering could be kept aligned with the architecture, integrating seamlessly the two with the construction methods, standards and technology.The preliminary design process consisted of three major phases: •,geotechnical and geological issues, preselection of construction methods; •,functional scenario based on engineering and construction requirements; •,review and merging of the architectural concept with the functional and engineering aspects. The last phase proved the most demanding one, matching the first outline sketches with the applicable construction methods. This required continuous alignment of approaches, eventually leading to the design consistent with the original architectural vision, yet fully compliant with the engineering and construction framework. At the beginning general information on Line 1 will be provided, followed by some main features of the construction work along the Dante – Garibaldi section both for the tunnel and the stations. At the end, the selected methodology and the related consequences on the functional, technical and architectural design will be outlined.City of Naples current municipal transportation plan envisages a circle ring line for the metro line M1. Actually it’s open to public the segment Piscinola – Dante – Garibaldi run by AMM, municipal company. This ring segment has been built by Metropolitana di Napoli, while Napoli Metro Engineering (company belonging to MMspa Group) is in charge for the planning of entire system and construction management. Line 1 connects Piscinola-Secondigliano northern periphery to Vomero shopping neighborhood, downtown and Central Railway Station."

Jan 1, 2016

By Albert W. Deurbrouck

The coal reserves in the United States are estimated to be in excess of 300 billion recoverable tons, and current projections of energy requirements indicate our increased dependence upon these reserves. The Department of Energy's Energy Outlook for 1984 projects that coal consumption in the United States will increase from 737 million tons in 1983 to 958 million tons in 1990, and then to 1,110 million tons in 1995 (Table 1). As shown in this table, the future utilization of coal in the United States is closely tied to the electric utility market, a market that consumes about 85% of the coal produced. Be- cause of this dependence on the utility market, the uncertainties of new environmental regulations, particularly those concerning sulfur emissions, could have a significant adverse impact on future coal demands in the United States. SULFUR IN U.S. COALS Most of the Nation's coal reserves contain too much sulfur to be fired directly and meet existing emission control standards. In Table 2, the sulfur contents of the coals of the eastern United States are summarized by sulfur levels according to regions. While the coals of some of the eastern regions are predominantly high in sulfur content, it is important to recognize that large tonnages of coal with relatively lower sulfur content are available in these regions. Furthermore, an often significant portion of the sulfur occurs in the form of iron sulfide (Fes2 or pyrite). Because pyrite occurs as discrete particles of high specific gravity, it can often be removed by simple, inexpensive physical coal beneficiation techniques after being liberated by stage crushing. The potential for physical removal of pyrite by conventional specific gravity processes combined with stage crushing is summarized in Table 3 on a regional basis.

Jan 1, 1986

By D. Johann, E. Zanetti, I. A. S. Brum, P. M. Zancan, A. F. Castro

"This study was done from a sample of coal mined at the Vale-Mozambique mine, located in Moatize district, Tete Province. The aim of this work is to analyze the reagent system in the flotation of coal fines belonging to the Upper Chipanga layer (UC). Among coal processing methods, flotation stands out as one of the most important for the concentration of this material, in particular in the treatment of fine particles. The total feed of the Vale-Mozambique processing plant is 8,000 tph of coal, where 10% of this feed corresponds to the fine fraction that feeds the flotation circuit. The material used in this study had a particle size of 96% smaller than 0.25 mm. The reagents used in the flotation tests were betacol and diesel oil as hydrophobizing agents and MIBC as frother. The range of betacol concentrations in the first test phase was 200 g/t to 500 g/t, and in the second phase 200g /t to 500g /t while diesel oil and MIBC were kept constant at 300 g/t. The immediate analysis followed the Brazilian standards NBR 8289, NBR 8293, NBR 8290; and NBR 8299. The results showed that it is possible, from a feed with ash content around 22.84%, to obtain products with levels below of 10% ash, with a mass recovery around 50%. The recovery of carbonaceous matter was also evaluated and presented positive results. Complementing this study, the effect of H2O recovery was evaluated and it was observed that for the concentrations of betacol the recoveries ranged from 6 to 9%, and for diesel oil plus MIBC were 4 to 7%.INTRODUCTION Considering the increase in population and energy consumption as humanity has been living along the last decades and the consequent demand for non-renewable natural resources, it is clear the challenge of the mineral industry in the search for new technologies and improvement of the existing ones. This challenge is justified by the need for better industrial results and to meet the market specifications, taking into account the reduction of deposits with higher contents and the need for beneficiation of more complex ores, lower levels and lower release granulometry. Usually in these situations, processes already well-established as the gravimetric (Sampaio and Tavares, 2005) have not good results."

Jan 1, 2018