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By F. W. Bryan, D. H. Lynch

Introduction This paper is a general description of current central Florida phosphate mining, beneficiation, and product transportation. It is directed and believed to be of interest to engineers not familiar with this industry. Deposit: The phosphate deposits of central Florida are generally located in a five county area which includes Polk, Hillsborough, Hardee, Manatee, and DeSota counties. Geologically, the deposit is of marine origin and is identified as the Bone Valley formation. This formation is Pliocene to Recent in geological age and overlies a Miocene limestone formation known as the Hawthorn. The Bone Valley formation sediments are regionally characterized by equal proportions of apatite, quartz, and clay. The clay is predominantly of the mont-morillonite family. On a local scale, however, the proportions of these three major constituents vary considerably. The phosphate occurs as the apatite mineral (Ca 10F2(PO4)(6) and with the clay and sand, the minable ore is commonly referred to as matrix. This matrix is overlain by unconsolidated overburden of sand and sandy clays, ranging in depth from 10 to 45 ft. The matrix usually occurs in fairly horizontal continuous beds from 3 to 25 ft in thickness. The bedded limestone formation lies directly below the matrix and is generally well defined. The phosphate particles range from 3/4 in. to 200 mesh (Tyler) in size. The phosphate particles coarser than 14 mesh are called pebble phosphate and those less than 14 mesh are termed flotation feed which, when beneficiated, subsequently become concentrates. Through mining and beneficiation, phosphate quality is measured in BPL percent which stands for bone phosphate of lime units. In subsequent chemical manufacturing, the quality is indicated by P205 content. The deposit is economically characterized by various ratios such as tons of product per acre and cubic yards handled per ton of product. Magnesium, iron, and aluminum content are also considered in evaluating ore reserves. These elements are often critical to the chemical fertilizer processes. Presently, an ore body is considered economically minable if it meets the criteria shown in [Table 1]. These, of course, are general guidelines and specific costs and returns on investment must be considered in each case for acquiring reserves. On a new grass-root venture, a 20-30 year life is generally expected with a mineral recovery of 80%. History and Uses Phosphate mining in central Florida began around the turn of the century. However, in the early days, only pebble phosphate was produced until about 1930 when technology was available to beneficiate the -14 + 150 mesh particles. The -150 or -200 mesh material was discarded as it is today. The basic processes for beneficiation are washing, scrubbing, desliming, sizing, and flotation. These basic unit processes are essentially the same today although many improvements have been developed since the early days. Phosphate is used primarily in the production of high analysis fertilizer chemicals, typical of which are triple superphosphate, monoammonium phosphate (MAP), and diammonium phosphate (DAP). Phosphate is also used in the production of food preservatives, dyes for cloths, vitamin and mineral capsules, steel hardeners, gasoline and oil additives, toothpaste, shaving creams and soaps, bone china dishes, plastics, optical glass, photographic films, light filaments, water softeners, insecticides, soft drinks, road fill, and livestock feed supplements. Florida produces over 80% of the nation's marketable phosphate rock and one-third of the world production, according to the US Bureau of Mines. This amounted to approximately 35 million tons in 1975. Exports of Florida phosphate rock were to such countries as Canada, Japan, West Germany, Italy, and India, with Canada and Japan being the major users. Almost 95 o of all outbound cargo shipped through the port of Tampa is phosphate rock or related products. Beneficiation Following is a description of Agrico's new Fort Green beneficiation plant which is typical of the newer large capacity plants being built in the field. Agrico's Fort Green mine was completed in 1975 and is located in the southwest corner of Polk County and is directly adjacent to Manatee, Hillsborough, and Hardee Counties. With some minor differences, Fort Green is typical of a modern central Florida plant. The rated capacity is 3,000,000 plus tons of product per year and this varies according to the richness of the ore being handled. A simplified flowsheet is presented in [Figs.1 and 2]. This plant is served by three draglines of the 40-cu-yd class. The phosphate beneficiation is usually divided into three major functional steps: (1) washing and screening to produce a pebble product and flotation feed, (2) feed preparation and (3) flotation to produce concentrates. The typical plant is similarly divided into these three functional areas. Washer: Briefly, the slurried matrix is pumped from two draglines simultaneously at a combined rate of about 20,000 gpm at 2000 tph (solids) to rotary trommel screens sized to make a 7/8-in. separation. ([See Fig. 1]-) The trommel oversize is sent to hammermills where it is crushed and returned to the trommel screens, or pumped to tailings if minor impurities (Fe203, A1203, MgO) are too high. The trommel undersize is pumped to 14 mesh stationary (static) flat screens. The flat screen over¬size is subjected to three stages of 14 mesh vibrating screening and two stages of log washing in order to produce a final pebble product. The pebble product (+ 14 mesh material) is conveyed by belt conveyor to a large on-ground storage pile. Pebble product is reclaimed through a tunnel and loading system below

Jan 1, 1980

By William H. Dresher

The crust of the earth, together with its seas and its atmosphere, is the source of all of mankind's primary wealth. Indeed, most people think of precious metals and stones when they think of wealth mined from the earth, but the value of the material and energy goods derived from the earth far exceed the value of the precious metals and gem stones. Thus, it is obvious that all minerals which we mine from the ground represent new wealth--the copper, clay, or petroleum we mine just as much as the gold or silver. More and more, wealth is defined in terms of utility-not in terms of an arbitrarily established monetary value. The recent action of the OPEC nations in controlling the flow of petroleum has clearly demonstrated this to the petroleum-importing nations! There is developing in the United States, as well as in many other nations of the world, a concern for the future availability of many mineral-derived raw materials and of mineral fuels. Ore grades are diminishing, concern for the environment has placed restraints on commercial development of some mineral deposits and the processing facilities necessary to exploit them, and countries upon which we have relied for major mineral materials have become increasingly nationalistic, causing uncertainties in future supply and causing an increasingly alarming deficit in our nation's balance in trade.

Jan 1, 1980

By R. J. Tocher

Uniaxial testing was performed on coal specimens to determine the time-dependent response. The testing was carried out on coal from six mine sites throughout the Western United States and Pennsylvania. Testing configurations were varied to allow analysis of moisture dependency, stress level and specimen orientation. Several theories were presented for the behavior of coal due to moisture diffusion. Experimental results showed the correlation between the theories and the actual material response. Coal deformation was found to be highly dependent on the moisture level of the testing environment. Moisture migration causes drying and shrinkage which lead to progressive degradation of the material. The coal tested experienced a rebound if saturated after a period of drying. This type of time-dependent behavior overshadows the dependence on the applied stress level, which, however, still produces a noticeable creep behavior. Analysis of one series of creep test results was performed. A relationship was developed on the basis of a simplified rheological model to describe the coal response to uniaxial stress. Previous empirical formulations in the form of power laws were compared and their deficiencies pointed out.

Jan 1, 1980

By Franklin B. W. Woodbury

The Bureau of Mines, as part of its goal of helping maintain an adequate supply of minerals to meet national economic and strategic A needs, is evaluating alternative technologies to treat oxidized taconites. Since process control is an essential element in the application of these process technologies, research was performed on a prototype monitoring system utilizing a Californium-252 (252-Cf) neutron source and a thermal neutron capture-gamma ray spectra analysis method to measure the amount of iron and percent solids in process slurries. The prototype system was used to monitor the concentrate and tailing streams in a 900-lb/hr flotation pilot plant during continuous around-the-clock tests. The iron content of the process slurries was determined by measuring the total peak areas under the capture spectrum peaks at 7.626-7.632 MeV, the associated escape peaks at 7.136-7.122 and 6.626-6.612 MeV, and the iron doublets at 4.900 and 4.998 MeV. A potential method for determining the percent solids in process slurries using the 2.22 MeV hydrogen capture peak is discussed. Results of this work demonstrate a potential method for providing process control parameters using the data from thermal neutron capture-gamma ray reactions.

Jan 1, 1980

By T. L. Carpenter

"The presence of excessive water in the Gibraltar East Stage 1 pit initiated studies into the ground-water conditions that might be expected in mining the Granite Lake and Pollyanna pits. Hydrologic information obtained from a pump test program in 1974 indicated that deep-well dewatering could be successfully achieved. In 1976, a deep-well dewatering system consisting of eight wells was installed on the periphery of the Pollyanna pit . it has been responsible for a significant decrease in mining costs.This paper presents a brief summary of the engineering principles involved in the design of the Gibraltar dewatering system and the problems encountered in the installation and operation of deep-well pumps. IntroductionGibraltar Mines is an open-pit copper-molybdenite mine located approximately 230 air miles north of Vancouver in the central interior of British Columbia (Fig. I). The property consists of three separate major orebodies; Gibraltar East, Granite Lake and Pollyanna (Fig. 2). Mining commenced during the summer of 1971, in the Gibraltar East Stage 1 pit. The Granite Lake Stage 1 pit was mined from mid 1974 to mid 1976. The Pollyanna Stage 1 pit is currently being mined and the Gibraltar East Stage 2 is being developed for production. This report is intended as an outline of the studies and tests leading up to and including the installation of the Pollyanna pit dewatering system, the problems encountered and the results obtained.GeneralIn the summer of 1973, mining in the Gibraltar East pit progressed below ""daylight"" on the down-hill side and ground water very quickly became a costly nuisance in the day-to-day mining operations. Mining, maintenance and blasting costs reflected these problems. Concern was also voiced about adverse effects of ground water on pit wall stability. This concern later became a reality in the Gibraltar East and Granite Lake pits. A study was initiated to investigate various methods and costs of dewatering the pit areas. The study included in-pit sumps, deep peripheral wells and a drainage gallery system located below the pits."

Jan 1, 1980

By Y. Zimmels, I. J. Lin, I. Yaniv

The potential application of magnetic and electric separation techniques in beneficiation of fine-particle feeds are reviewed. Special features of these techniques are considered and compared with a view to increased amenability of such feeds to separation in electro- magnetic fields. The following techniques are discussed, with reference to those already developed and in use to-date: - Differential-susceptibility separation (DSF). - High-gradient differential-dielectric separation (HGDDS). - High-gradient magneto-gravimetric separation (HGMGS). In this context the new approach - whereby selectivity of solid- solid separation processes, in wet high-gradient magnetic and electric separation, can be improved - is described, including experimental results from DSF and HGDDS tests.

Jan 1, 1980

By A. G. Galaitsis

The two volumes of this report summarize the noise control work performed by BBN on a rail personnel carrier operated in coal mines. Volume I of the report - submitted November 1977 - describes the aboveground work performed to identify the noise sources, design, fabricate, and install the treatments, and evaluate the treatments through noise and vibration tests. The current volume (II)-describes the underground work conducted by BBN to determine the deterioration, if any, of the treatments when the vehicle is operated normally in a mine. There were no significant changes in the acoustical performance or mechanical integrity of the treatments at the end of a three-month period.

Jan 1, 1980

By Dragomir D. Kocic

At its lowest hierarchical level, the mine ventilation control system consists of local systems controlling the concentration of noxious gases in the air currents of various branches of the ventilation network, and of local systems controlling the air flow rates through those branches in which it is not necessary to regulate the concentration of any noxious gases. With respect to the noxious gas concentrations, the manipulated variables are air flow rates, while with respect to the air flow rates - the manipulated variables are aerodynamic resistances of the corresponding branches. Since there is an interdependence between the air flow rates in the ventilation network branches controlled through changes in aerodynamic resistance, the total system of mine ventilation control falls in the class of multivariable systems. The treatment of individual branches of a controlled ventilation network as separate plants presupposes an absolute autonomy of local systems, which is an untenable concept. The present paper is an attempt to break up the multivariable control system of the noxious gas concentrations and the air flow rates into autonomous (mutually unrelated) local control systems. The plant discussed is a ventilation network of arbitrary configuration with a single main axial fan. Because of the complexity of the problems involved, the multivariable control system of noxious gas concentrations and air flow rates has been described as linear, with constant and lumped parameters.

Jan 1, 1980

By H. Wagner

The paper points out that bord-and-pillar mining is the most important method of coal extraction in South African underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata. However, any deviations from well-established design procedures must be based on sound engineering principles and reliable data on the strength properties of the seams and strata concerned. Recent information indicates that practices for the protection of surface structures against underground mining should be revised.

Jan 1, 1980

By David E. Siskind

The Bureau of Mines has studied the problem of cracking in residential structure walls from vibrations produced by blasting in surface mines. Direct observations were made of blasting damage consisting primarily of cosmetic cracking in plaster and gypsum board walls. Measurements of structure response and also application of the response spectra analysis single-degree-of-freedom model were used to quantify the frequency dependence of the safe level criteria. An overall summary analysis was performed using the new Bureau of Mines damage observations and data obtained from nine previous studies, including the three analyzed earlier by the BuMines for Bulletin 656, published in 1971. Separate analysis of the high- and low-frequency damage cases, structural response, and two types of construction resulted in the establishment of safe vibration levels ranging from 12 mm/sec to 50 mm/sec (0.5 in/sec to 2.0 in/sec).

Jan 1, 1980

By Douglas W. Fuerstenau

A detailed experimental study of breakage kinetics in a batch rod mill indicates that while the system is inherently nonlinear, the feed disappearance kinetics for the finer sizes and the coarser sizes at high holdups is well represented by first-order behavior. The set of breakage distribution functions was found to be normalizable and independent of particle holdup in the mill. The size discretized initial breakage rate functions were found to be inversely proportional to particle holdup and almost directly proportional to particle size. A linearized grinding model that results from the first-order Taylor's series expansion of the breakage rate expression was found to give good simulations of the mill product size distributions without recourse to any parameter improvement routines. Material transport through rod mills was evaluated by investigating the effect of operating variables on the holdup and residence time distribution of particulate solids flowing through the mill. Identical experiments performed in a continuous ball mill helped delineate the fundamental differences in particulate transport through these two types of mills. Mechanistic interpretations of the observed transport phenomena are presented, and their implications in the context of tumbling mill analysis and design pointed out.

Jan 1, 1980

Presiding-Thomas R. Young, President, Wyoming Fuel Company, Lakewood, Colorado. Mark Gillaspie, Vice President, San Marco Pipeline Company, Houston Natural Gas Company, Houston, Texas, presented a very interesting film-"Invocation in Coal Transportation-Black Mesa Coal Slurry Pipeline." (See index for printed text of Mark Gillaspie's remarks) * * * Kaye Kuhlmann, President of Citizens for Total Energy, San Jose, California, presented a paper-"Grass Roots Support for Energy Policy." (See index for printed text of Mrs. Kuhlmann's paper.) Mrs. Kuhlmann is President of Citizens for Total Energy, an International volunteer grassroots organization with the purpose of educating the public on energy alternatives. CITE strongly advocates responsible citizen participation in the establishment of energy policy.

Jan 1, 1980

By J. Bennetts

As part of its mission to develop technology that will help increase the supply of critical and strategic minerals from domestic resources, the Bureau of Mines has investigated methods for beneficiating platinum-group metal ores from the Stillwater complex, Montana. This report presents the result of a bench-scale study employing froth flotation to recover a sulfide concentrate containing platinum-palladium values from a mineralized gabbro. Best results were obtained with a flotation scheme utilizing a mercaptobenzothiazone collector and sulfuric acid. Rougher concentrates containing approximately 11 oz Pt-Pd/ton and 90 pct of the metal values in the ore were obtained. Subsequently, cleaner concentrates containing approximately 26 oz Pt-Pd/ton and between 80 to 85 pct of the Pt-Pd values in the ore were prepared.

Jan 1, 1980

A laminar-flow furnace was used to study the combustion of four flotation concentrates (chalcopyrite, pyrite, galena, and sphalerite) in air at temperatures up to 1400¦C. A special- Iv developed two-colour pyrometer was used to measure the temperature of individual chalco- pvrite and pyrite particles as they underwent combustion. Chalcopyrite and pyrite ignited with very high rates of reaction at air tempera- tures above 480 and 600¦C respectively, forming molten products. Galena and sphalerite required temperatures in excess of 700 and 1200¦ respect- ively to attain equivalent rates of reaction. The high rates of reaction for galena and spha- lerite were caused by vaporization. Temperature measurements for chalcopyrite and pyrite are reported here, together with vaporization measurements for chalcopyrite, galena, and Sphalerito

Jan 1, 1980

By B. Gilbertson

This paper presents a method that enables one to estimate the risk-adjusted discount rate. that should be used In project discounted cash-flow analysis. The risk-adjustment process is carried out via the capital asset pricing model of modern finance theory, in which the appropriate measure of risk is the beta coefficient of the project concerned. The resulting discount rate thus depends on the properties of the project Itself, and not on the nature or cost of the capital of the firm considering the investment.

Jan 1, 1980

By I. I. Inculet, M. A. Bergougnou, J. D. Brown, R. M. Quigley, D. K. Faurschou

"Coal from Hat Creek, B. C., has been successfully beneficiated to remove ash while retaining calorific value by a dry electrostatic separation process using a fluidized bed for triboelectrification. Two samples of Hat Creek coal used in the beneficiation experiments have been characterized particularly with respect to their mineral and clay content. The calorific value recovery exceeds the simple dry coal recovery because of the heat lost in altering the clay minerals of the ash fraction during burning. Recoveries and ash contents of the beneficiated coal are comparable to recoveries by water washing, but the dry process avoids the potential water pollution problems.IntroductionProposals have been made which suggest an interim Canadian coal production target for the end of the century which will require a four- to fivefold increase over the 1977 production. This implies a nominal annual growth rate of about 6070 to achieve a production rate of 115 to 140 million tonnes/year. Whether or not this target is realistic, it is becoming increasingly evident that coal must be utilized more fully on a world-wide basis. The crisis in Iran has provided the latest stimulus to renewed interest in Canadian coals for domestic use and export.The emerging new era of coal utilization for fuel and chemical feedstock will not, however, generally tolerate the level of coal technology which prevailed prior to the availability of abundant cheap oil and natural gas. Economic, environmental and resource management considerations will necessitate, for example, the use of improved methods of beneficiating coal. Continued development and application of conventional processes, principally aqueous, involving heavy media and cyclones will solve many of the problems. However, less conventional processes may be preferable or necessary in certain applications."

Jan 1, 1980

By A. S. Speirs

Over the last few years, the never-ending search for mineral wealth has taken the exploration efforts of Canadian mining companies further and further into the High Arctic and isolated locations where regularly scheduled transportation and communication facilities are nonexistent. Names such as Black Angel, Nanisivik, Asbestos Hill, New Quebec Raglan, Rabbit Lake, and Arvik are today frequently mentioned in mining publications. Twenty years ago, mining in these locations was unheard of, mainly due to logistic problems. However, improvements in the design and use of helicopters, STOL aircraft, and icebreakers in northern areas have helped to overcome these problems, making these locations more attractive to mining companies. Since 1969, when Redpath completed its first Arctic project at Texas Gulf's Scrathcona Sound property on the northern tip of Baffin Island, Redpath has been actively involved in contracting and engineering projects in three general areas: the High Arctic, Ungava and Greenland. A map showing some of these projects is shown in Figure 1. In these areas, permafrost conditions exist from a depth of 274 metres in Ungava to a depth of approximately 610 metres in the Little Cornwallis Island area, with rock temperatures ranging from -5°C to -13°C. Outside temperatures range from a low of -50°C in the winter to a high of 21°C in the summer. High winds in the winter result in wind chill factors lower than -73°C

Jan 1, 1980

By Michael J. Taylor

Introduction A prime goal in the design and operation of uranium milling waste or tailing disposal systems is to mitigate adverse effects of tailing liquid on the adjacent groundwater. Adverse effects are often defined as modifying the groundwater quality in such a manner as to have detrimental health effects on downstream users. To accomplish this goal, the following three types of systems are employed with regard to the seepage and groundwater aspects of waste disposal: Type I Systems Seepage is allowed to occur unabated from the tailing disposal facility. Detrimental radionuclides and chemical elements are prevented from causing adverse downstream effects by natural purification actions in the subgrade geologic materials and the near zone groundwater. Monitoring is required to assure the predicted natural purification is occurring. The consequences of seepage loss is minimal since the m be predicted with current investigation and analytical techniques and can be evaluated as to effectiveness during operations. Type II Systems Seepage is partially retained in a waste impoundment or leakage from a designed retention system is anticipated. Natural purification is relied on for controlling migration of detrimental radionuclides or chemical elements, or contingency planning is employed to collect and return the tailing liquid to the impoundment. Installation efforts and concern for escape of tailing liquid are greater than for Type I systems, but extra precautions to preclude all seepage are not implemented. Monitoring is required to detect leakage and/or assure the natural purification of escaping tailing fluid. The consequence for accidential excusions are moderate, and will be excessive only if massive system failure occurs. Type III Systems Seepage is totally restricted by a costly system constructed and operated with extra care. Natural

Jan 1, 1980

INTRODUCTION Mineral explorationists range throughout the world looking for mineral deposits which can subsequently be made into mines. Mines are not found! Mines are made, usually at great cost and not often without significant risk. The process of making a mineral deposit into a mine involves a great deal more than a complete appraisal of the deposit. The making of a mine demands detailed feasibility studies of many factors, any one of which, if shown to be negative, could prevent the deposit from becoming a successful mine. Total feasibility analysis involves at least three major fields of study: (1) economic analysis, (2) financial analysis, and (3) political and environmental analysis. Economic analysis is essential for proper decision making at many stages in the evaluation of a mineral deposit. It is the yardstick by which the proposed mining project and alter- native investment opportunities are measured. Economic analysis is concerned with costs and potential profits and can be applied at various stages in the evaluation of a mineral deposit to determine if the project merits the additional funds necessary to bring about each succeeding stage. The nearer any deposit approaches to becoming a mine, the more carefully the economic analysis should be made. Financial analysis has reference to how, where, and at what cost the investment funds can be obtained to finance the proposed mine project. Political and environmental analysis has reference to the many intangible factors that can affect the making of a successful mine. These factors loom larger today than ever before, due to the profusion of government regulations and various environmental constraints now imposed upon the mineral industry both by law and by the weight of public opinion. Ultimately, many of these intangible factors can be resolved back into the economic analysis as an added cost to mine development, but more and more often they have become insurmountable obstacles to any development of certain deposits. The role of financial analysis and the analysis of intangible factors must never be underestimated when making a feasibility study upon which to base investment decisions; however, the emphasis of this text will be upon economic factors. THE PARAMETERS OF MINERAL ECONOMIC ANALYSIS The two major elements of economic analysis are: 1) The potential earnings or annual generated cash flow of the project. 2) The investment costs necessary to realize such earnings. If the difference between the two elements is large enough, i.e., if the return on investment from the cash flow is high enough to attract investors, the project can be said to be financially feasible. The mineral economic analysis must take into consideration many parameters, some of which are known or knowable within certain limits, and others of which are unknown or unpredictable within certain limits and for which estimates must be made. Because both known and estimated parameters enter into the same analytical computations, it is important for the analyst to realize the nature of each when considering the results of an analysis. Some parameters such as the grade of mining block, although estimated, are said to be known within mathematically defined limits. Other parameters, such as the future price for minerals produced, etc., can only be estimated or "guestimated" within reasonable limits for which no precision can be assigned. Known or Knowable Mineral Economic Parameters Known or knowable parameters are: 1) Tonnage and grade of valuable minerals for the total mineral body and for individual mining blocks. 2) Metallurgical recovery of valuable mineral. 3) Minimum operating life of mineral de- posit at any specified production rate. 4) Royalty schedule, property payments, etc. 5) Sales-purchasing agreements, smelter schedules, marketing contracts, etc.

Jan 1, 1980

By M. A. Upham

"Prairie Evaporites of the Province of Saskatchewan in a deep oil-well hole. Exploitation started in 1950 under a shroud of doubt that this huge reserve could be mined. It was fraught with almost insurmountable physical problems in penetrating the Prairie Evaporites. After 12 years of experimentation and development of new shaft-sinking methods, mining equipment and processes to treat the high-grade potash ore (sylvanite), a new era of high-risk resource development dawned in Saskatchewan.The development of 10 new mines opened up the largest known mineable potash reserves in the world and Canada became the second largest. producer of potash to supply domestic (U.S.A. and Canada) and overseas markets. A monumental program in marketing-devising new transportation systems and strategically locating warehouses-was developed in order to expeditiously service domestic and overseas customers. The year 1969/70 started a period of overcapacity and the problem of prorationing. As the market strengthened in 1974, the Saskatchewan Government applied the reserve tax to the industry. Then, they announced the setting up of a Crown corporation to acquire ownership by purchase of up to fifty per cent of the industry. During this time, potash was discovered in New Brunswick within 50 to 60 miles of a seaport, where two deposits have been explored by the same pioneers who started the potash development in Saskatchewan.With this background, the paper will examine various elements of the economics and marketing of Canadian potash."

Jan 1, 1980