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By A. W. Jenike

Mine backfilling is a desirable method for the disposal of retorted oil shale. Hydraulic, mechanical and pneuna.cic transport and stowing methods were investigated, and the mechanical transport and stowing method using conveyors was selected as the most promising system. Transport of retorted oil shale at the rate of 3000 cons per hour (2700 t(h) to the backfill level, situated about: 2000 feet (610 m) below surface, with skips or conveyors is uneconomic. Hence, borehole transport utilizing gravity flow was investigated. This paper describes the theory of flow, flow properties of retorted oil shale, and the design of a borehole and hopper system.

Jan 1, 1978

By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By B. T. Darnton

Gravity concentration at the Pegasus Gold Montana Tunnels Mine was initiated in late June, 1991 with the commissioning of a coarse gold scalping circuit that processes a small portion of the ball mill circulating load. The primary objective for the circuit was to reduce the risk of gold particles advancing to flotation that are too coarse to float. The secondary objective was to enhance overall gold recovery and payable gold ounces in a cost effective manner. The gravity circuit has proven itself to be a major success. The above mentioned goals have been achieved, and they have been maintained at record throughput rates that are 30% higher than when the circuit was commissioned. A number of modifications and improvements were made over the last three years which allowed the gravity circuit to keep pace with the higher tonnage, these are discussed in detail in the body of this paper. The overall approach to gravity concentration at Montana Tunnels has always been to optimize production rather than maximize the gold ounces produced. This philosophy has now yielded a circuit expansion and relocation project which will allow for an estimated 50% increase in gravity gold production, while reducing the overall unit costs of production significantly. This paper will review historical gravity circuit performance, improvements, and the current relocation and expansion project.

Jan 1, 1995

By L. L. Damon

A geochemical study of cyanide neutralization processes was conducted at Brohm Mining Corporation to gain a better understanding of the leach pad behavior and to develop a simplified procedure to quantify the attainment of compliance with permitted cyanide neutralization criteria. Such attainment is a prerequisite for off-loading spent ore from the leach pad at the "load/unload" gold heap leach operation. The geochemical study program consisted of size fraction analyses and weak acid dissociable (wad) cyanide analyses for various sections of the spent ore from the actual leach pad. Further testwork included size fraction analyses and wad cyanide analyses on the ore from four 29 foot laboratory test columns which were leached and neutralized with different neutralization treatments in parallel with an actual active leach pad. Wad cyanide was analyzed daily on the neutralizing columns and various parameters were monitored weekly on the influents and effluents during the leach cycle and neutralization period. A comparison was made of neutralized effluent chemistry and porewater extraction fluids, as well as an analysis of the selective adsorption of cyanide on various particle size fractions.

Jan 1, 1992

By S. Mischler, J. Noll, G. Schnakenberg, A. Bugarski, M. Crum

Diesel particulate filter (DPF) systems and biodiesel fuels are two of the most promising technologies available to the mining industry to reduce the exposure of underground miners to diesel particulate matter (DPM). A study has been conducted to estimate the potential of DPF systems and biodiesel blends to reduce DPM emissions from production vehicles. Results of testing three DPF systems in an isolated zone showed 88% to 99% reductions in elemental carbon concentrations. The test results also show that biodiesel blends, B20 and B50, reduced the elemental carbon concentrations in the mine air by 26 and 48 percent, respectively.

Jan 1, 2004

By Philip M. Rice, Paul Schmall, Peter W. Deming, Hugh S. Lacy

A groundwater cut-off is needed to provide a stable face of tunnels to be constructed by jacking precast rectangular tunnel segments beneath commuter rail tracks for the new I-90 extension in Boston, MA. Extensive obstructions are present within the path of the tunnels. This paper describes how the use of artificially frozen ground is being planned to provide a reliable groundwater cutoff and assure a stable tunnel face. Monitoring during freezing assures continuity of the cutoff. Laboratory testing of frozen soil samples aided the design of this frozen soil boundary. Logistics of installing vertical freeze pipes are described.

Jan 1, 1999

By B. Ladanyi

An adequate knowledge of the overall behavior of a rock mass at a given site is fundamental to the satisfactory design of a rock slope. The be- havior is controlled by a variety of factors, in- cluding rock type, geological structure, stress and ground water conditions. There are essentially three lines of approach that may be used to obtain information on the in-situ rock mass behavior for the purpose of the design of a rock slope: (1) Direct measurements of rock mass properties by means ol laboratory and field tests. (2) Evaluation of rock mass properties from a study of slope failure case histories and sta- tistical information on stable and unstable natural rock slopes. (3) Evaluation of in-situ behavior of rock mass by using a physical or mathematical model technique.

Jan 1, 1980

By Pierre J. Wauters, Eddy J. Jacques

Starting up a fan or modifying its setting point either by rotational speed variations or blade angle changes, obviously results in new ventilation conditions in the network, which is, of course, the object of the operation. However, since transient phenomena may then occur, particularly in complex networks, there may be a need to simulate these situations prior to any action. This is all the more true, if we are dealing with a multiple interactive fan sys- tem. Simulations with a transient model have shown that the flow in certain airways could be temporarily reversed due to the pres- sure variations that reach both its ends with a different time lag. This phenomenon may cause dangerous situations to occur in cases of fire or outburst of methane. It is also true that the air flow could be reversed in secondary and less powerful fans, while still rotating in the normal direction. The study and the experimental investigation of the extension of the reverse flow characteristic is therefore justified from two points of view : • a numerical simulation model for transient flow conditions must be capable of handling temporary reversed flows, and thus have appropriate fan characteristic curves available over the entire operating domain; • while operating fans, reversed flows should be avoided or at least reduced. Therefore, the design of start-up procedures or real time control algorithms should take these phenomena into account. A particular interesting application is the operating of two fans in parallel. In order to investigate experimentally the characteristic curves of a fan under reversed flow conditions a small scale model was built. This facility was designed in such a manner that it was possible to carry out experiments concerning flow reversions and to try out sequential start-up procedures for two fans in parallel.

Jan 1, 1997

By Jianbo Hu, Tao Zheng, Zhao Qihua, Rui Su

Rock mass discontinuities play a significant role in evaluating the stability of rock slopes. It is necessary to collect and analyze these discontinuities to fully understand the mechanical and deformational behaviors of rock masses. Based on the digital images of some slope faces, this paper proposes a framework based on machine learning for detecting and extracting discontinuities. First, digital images and photo poses are combined, the original scene is reconstructed, and 3D point cloud data are obtained. All captured point clouds can be mapped with each image by the direct linear transformation algorithm. Next, the detection machine learning algorithm is used to segment rock mass discontinuities on 2D digital images. Finally, based on the mapping relationship, the 2D digital images that were segmented are transformed into 3D point cloud data. The geometric parameters of the corresponding discontinuities can be extracted by the DBSCAN and the Skmeans algorithm and the characterization of specific rules. The proposed framework was evaluated utilizing a quantity of slope digital images in the Yebatan hydropower under construction, located in Sichuan Province, China, as a case study. The results illustrate that most deviations are less than 10° for the dip direction and dip angle, which verifies the reliability of the proposed framework and maintains acceptable measurement accuracy.

Nov 6, 2022

By John L. Ellenberger

Virtually no two mines operate with the same geographic, geologic, and mining conditions. It follows chat problems vary with the conditions from mine to mine or often from one section to another in the same mine. Actual situations are described, and a technique of "stacking" maps to predict hazards is presented. Two case histories of the use of multiple overlays are de- scribed. The first deals with a property that was examined before the start of mining. The second is a property in which severe ground control problems were encountered and the relationship between the problem areas and known conditions were found to be related.

Jan 1, 1981

By T. O. Kuhl

The Royal-Mountain King Project is 7.2 kilometers (4.5 miles) northwest of Copperopolis, California. Reserves of 8,250,000 t (9,100,000 st) at 2.32 g/t (0.068 oz/st) gold will be processed at 2500 t/d (2750 st/d) from three pits. Production is scheduled to begin the first quarter of 1989. District geology consists of northwest trending sequences of Jurassic meta-sedimentary and meta-volcanic rocks. Three ore bodies are located along the Hodson fault which trends northwest and dips 40 degrees northeast. The Gold Knoll and North Pit ore bodies are hosted in carbonate and silica altered meta-volcanic rocks whereas the Skyrocket ore body is hosted in quartz stockwork zones in meta-sedimentary rocks. Gold is present as inclusions and micro-veinlets in pyrite.

Jan 1, 1989

By John C. Balla

The Troy deposit is located in northwestern Montana, approximately 17 mi south of Troy. The deposit is a stratiform, strata- bound, copper-silver deposit which occurs in the Revett formation of the Proterozoic Belt Supergroup. The Revett formation is approximately 1730 ft thick in the vicinity of the Troy deposit, and is divisible into three units. The upper Revett, approximately 250 ft thick, is the host for the orebody. The Revett represents a deltaic environment. The Troy deposit was discovered by Bear Creek Mining Company in 1 963 during the course of a reconnaissance stream sediment sampling program that was designed to discover strata-bound copper deposits. The deposit is approximately 7500 ft long, 1800 ft wide, and averages 60 ft thick. It is bounded on the north by outcrop, on the east by a post-mineral fault, on the south by diminishing grade and post-mineral faults, and on the west by diminishing grade. Ore reserves are 64 million tons with a grade of 0.76% Cu and 1.58 oz Ag per ton. The mine is presently operating at a production rate of 4.2 million oz of silver and 20,000 tons of copper per year.

Jan 1, 2013

By Yuting Xue, Mark Van Dyke, Zoheir Khademian

Borehole scoping has been widely used in the U.S. underground coal mines as a method for geologic mapping and stability analysis because it is very useful for identifying rock types, voids, fractures, and formation boundaries through the direct observation of the borehole wall. An image stitching technique was proposed to generate panoramic borehole images from side-view borescopes in a previous study. However, the generation of panoramic borehole images can be affected by the borehole condition because the image stitching process highly depends on the key point detection and matching. The presence of dust and water could have a significant influence on the detection of key points. In this study, the influence of borehole conditions on panoramic borehole images was studied from the success of image stitching and the visibility of geologic features and lithology changes. Borehole videos recorded at different times, when the same borehole was freshly drilled, freshly washed with water and 12 days after washing, were processed with the proposed technique. The comparison of the stitched images shows that the presence of dust has minimal influence on the image stitching process but shows significant negative effects on the visualization of geologic feature and lithology change. In addition, the presence of water can significantly hinder the image stitching process, which in turn helps in identifying lithology change. Borehole scoping aids in identifying and mitigating hazardous conditions in underground mines, and this study provides preliminary inputs into identifying optimum borehole conditions for geologic mapping with panoramic borehole images.

Feb 1, 2025

By George Wilson

When pumping abrasive slurry mixtures, special attention must be given to pump design and construction. The second article in this two-part series describes some design features to consider when selecting centrifugal slurry pumps. Hydraulic Design Most centrifugal pumps are conventionally designed to achieve the desired hydraulic performance at the highest efficiency and lowest cost when handling clear fluids in reasonably clean environments. Manufacturing limitations are not imposed on the configuration of the pump, since conventional materials such as cast iron, bronze, and stainless steel are used. Manufacturers and buyers usually select the highest specific speed commensurate with the lowest cost attainable. Part life is almost infinite. When a centrifugal pump is designed for slurry service, the important factors in pump design are wear and materials of construction; size and efficiency assume lesser importance. The pump must operate at low rotational speed and the impeller has to be a truly radial flow design. These factors immediately determine that the pump must be of a low specific speed design in the range of 600 to 1800. The specific speed is a type number that is constant for all geometrically similar pumps; it designates the geometry of the impeller and casing. [ ] where n = rpm, Q = flow (US gpm), H = total head (ft), and Ns = specific speed. Since wear is a function of velocity it can be shown that for a given head and capacity, wear will increase with increased Ns. Centrifugal Pump Casing The casing has a profound effect on performance. If designed incorrectly it can destroy a large part of the energy given to the flow by the impeller, resulting in low efficiency, high hydraulic forces, and excessive wear on both the casing and impeller. In a conventional spiral volute, the static pressure around the impeller is uniform only when there is a free vortex velocity distribution in the volute, i.e., when the spiral flow from the impeller coincides with that of the volute spiral. This occurs only at the best efficiency point (BEP), between the pump's best operating zone and over capacity zone. Departure from the free vortex velocity distribution in the volute at partial or over capacities produces circumferential pressure gradients at the impeller periphery, which is directly proportional to the specific gravity of the mixture being pumped. At partial or over capacities, the flow will not tolerate the abrupt deflection at the tongue and severe energy losses and wear are created near the casing throat and on the impeller. Concentric and semi-concentric volute designs produce uniform static pressures at the impeller periphery and make the pump, much less sensitive to "off"' BEP operation. Hydraulic forces and wear are considerably reduced-eliminating the tongue prevents abrupt deflection of the flow, turbulence is minimized, and the velocity in the casing volute and throat is reduced. Good efficiency is sustained over a wider operating hand. Casings of this design are easy to cast. • Spiral volute (conventional)-Radius to the outer periphery of the casing and the volute area constantly increases. • Semi-concentric casing-Radius to the outer periphery of the casing and volute area remain constant within a certain angle. • Concentric casing-Radius to the outer periphery of the casing and volute area remain constant through 360°. The degree of concentricity must be reconciled with efficiency, hydraulic radial load, and wear for each specific speed chosen. Up to 1200 Ns the casings can be fully concentric without sacrificing too much efficiency. Above 1200 Ns, the casings can be semi-concentric. The angle of concentricity

Jan 10, 1981

By Ning Wang, Tengfei Guo, Wanyan Li, Hanjie Wen, Hannian Gu, Zehai Li

Bauxite residue (red mud) is an alkaline waste derived from the industrial process for extraction of alumina from bauxite ore. Some bauxite residues contain considerable concentrations of critical metals, for example, rare earth elements. Lithium in red mud was also reported as a potential resource. In the current study, a Li-rich red mud was leached using acetic acid to investigate the leaching behavior of lithium followed by neutralizing with hydrochloric or oxalic acid. By neutralizing red mud using diluted hydrochloric acid (0.01 mol/L), 58.04–60.27% of lithium was leached using 25% acetic acid at 95 °C for 60 min. In the meantime, more than 95% of sodium and 85% of calcium were also dissolved in the leachate solution. While oxalic acid (0.5 mol/L) was used to neutralize red mud prior to acetic acid leaching, lithium performed lower leaching efficiencies (42.41–46.88%) in comparison of using of hydrochloric acid–neutralized red mud. Nevertheless, these leaching efficiencies of lithium were close to that of calcium and much higher than those of sodium under the condition. In this study, 25% (v/v) of acetic acid, at 85 °C for 60 min, was demonstrated as optimum conditions for lithium extraction from oxalic acid–neutralized red mud using acetic acid. The results would be useful and of interest for lithium recovery and purification from red mud.

By A. D. Paananen

With the demand for higher grade feed by the American steel industry and the depletion of the direct shipping ores from the Marquette Iron Range and elsewhere, there was a need to develop the low-grade orebodies. The large reserve of fine grained oxidized iron-formation at the Tilden Mine has been the object of research and development efforts to concentrate the iron oxides as far back as 1949. Preceding the present mining-concentration-pelletizing complex, about 6,500,000 long tons of direct shipping siliceous ore were shipped from the Tilden Mine. Following development of the concentrating and pelletizing flowsheets, engineering and construction was initiated to develop the mine and construct concentrating and pelletizing facilities to produce 4,000,000 LTPY of pellets from this low grade crude ore. Operations started in late 1974 with Algoma Steel, J&L Steel Corp., The Cleveland-Cliffs Iron Company, The Steel Company of Canada, Ltd., Wheeling-Pittsburgh Steel Corp., and Sharon Steel Corp. as participants. Cleveland-Cliffs operates and manages the operation. Due to the non-magnetic nature of the ore and the fine grinding required to liberate the iron oxide minerals, this crude ore was not amenable to concentration by conventional methods. The iron oxides of the Tilden orebody have a grain size of less than 25 microns and recovery of the finer, well-liberated iron oxides is essential. Conventional methods of des liming employing cyclones or thickeners were not feasible because of the excessive loss of iron oxides in the finer fractions.

Jan 1, 1978

By M. G. Vieira

This investigation addressed the possibility of producing pellet feed at a silica content of = 1.0% using a representative sample of Samarco´s mechanical flotation tailings. This sample contained 11.0% Fe and presented an F80 = 116 µm and a d50 = 63 µm. The higher silica content was verified in the coarser fractions and the higher iron content in the fraction -37 µm. Specular hematite is the most abundant mineralogical phase in the fraction -37 µm. The technological tests used one of four methods: magnetic concentration using a wet high-intensity magnetic separator, magnetic concentration using a SLon high-gradient magnetic separator, reverse flotation or direct flotation. The methods using the magnetic concentrator SLon, reverse flotation and direct flotation did not present results meeting the target of the study: iron content in the concentrate (rougher stage) greater than 34% or iron recovery greater than 80%. Cleaner stages were not achievable with the resulting concentrates. In contrast, the most successful method consisted of using wet high-intensity magnetic separators (WHIMS) as a rougher stage and reverse flotation as a cleaner stage. Using this route, it was possible to produce a pellet feed with a silica grade of 1.0% and high specular hematite content.

Jan 1, 2010

By Philip A. Mattson

INTRODUCTION Engineers involved with rock mechanics know the importance of discontinuities within a rock mass and their effect on its behavior when subjected to loads from structures or construction excavation activities. Various geophysical tools have been developed to provide comparative information on subsurface conditions, such as electrical resistivity, assorted seismic test methods, acoustic tests, etc. While these investigative means have proved invaluable in numerous situations, especially those where site alternatives are being evaluated, they shed little light on the difficult problem of quantifying the rock strength. For that purpose, a laboratory test program of samples obtained in the field is usually undertaken, often in conjunction with a variety of in-situ tests. While standard samples provide sufficient information on the rock properties, questions on the macro-structure of joints, faults, fissures, and their infillings often go unanswered. Presently, attempts are being made to incorporate into rock sampling technology new techniques which are directed towards providing better information on the incidense and orientation of discontinuities. One such device incorporates a scribe knife within the core barrel which scores the sample lengthwise as it is cored. The orientation of the scribe is known, thereby relating the bedding, planes, fractures, etc. to a spatial framework. A second approach, called the Integral Sampling Method, is the subject of this paper. Stated briefly, this method utilizes a grout injection to bond fractured rock to a steel reinforcing bar at the center of the coring. The bar is intended to act as a

Jan 1, 1979

By Frank E. Dalton, Forrest C. Neil

INTRODUCTION The Tunnel and Reservoir Plan (TARP) (Figure 1) was adopted in 1972 as the most cost-effective way to bring Chicago area waterways up to Federal and State water quality standards. TARP will significantly reduce pollution of these waterways and provide flood relief for Chicago and 53 adjacent suburban communities. These communities, covering an area of 971 sq km (375 sq miles), are at present served by combined sewers, which carry both raw sewage and stormwater. Because porous ground surfaces have been covered over in recent years by buildings, streets, and parking lots, stormwater runoff into sewers frequently exceeds the capacity of the sewers. When this happens, sewers back-up into hundreds of thousands of basements, and the overflows on the combined sewers discharge rainwater mixed with raw sewage directly into the area's waterways at 645 overflow points. The result is severe pollution of the waterways and flooding in 53 communities. During particularly heavy rains, overloaded rivers have to be relieved by opening the locks and allowing the polluted waterways to flow into Lake Michigan, the region's water source. Goals of TARP 1. PREVENT BACKFLOWS INTO LAKE MICHIGAN. 2. ELIMINATE WATERWAY POLLUTION CAUSED BY COMBINED SEWER OVERFLOWS. 3. PROVIDE AN OUTLET FOR FLOOD WATERS.

Jan 1, 1981

By James J. Fallen

In this paper we are going to look at some things that may happen to the industrial minerals industry in the next decade. First, some concepts and definitions. What are industrial minerals? Not everyone agrees on an answer to this. So let's look at some of the opinions. Some say that industrial minerals are non-metallic minerals. As you well know, metallic minerals are used as a source material for metals. Copper, lead, and zinc are extracted from metallic minerals. But, some metallic minerals are also used for other reasons. Bauxite is used as a source of alumina and aluminum. It is also used as proppant in well drilling, as an abrasive, as a refractory material, and as a source of aluminum-based chemicals. So bauxite is both metallic and nonmetallic. There are other examples, too. Bastnasite is a source of rare earth metals and alloys but its concentrate is used in fluid cracking catalysts. Phosphate rock is an industrial mineral when used for fertilizer, but it is also the source of phosphorus. Ilmenite and rutile are sources for titanium dioxide pigments as well as titanium. So the nonmetallic designation is not adequate to define industrial minerals. Some say industrial minerals are called such because they are consumed in industry. How about your cat's litter box? Is that industry? Huge amounts of montmorillonite, attapulgite and other sorbtive minerals are pelletized and calcined to make animal litter. Doctors are trying to get people to cut down on their salt consumption. They are against people eating industrial minerals. When diamonds are a girl's best friend, they are not industrial minerals; when they are grinding and polishing media, they are. These examples show that industrial minerals are not exclusive to industry. Regardless, here is my list of industrial minerals: Abrasive Materials - Bentonite Antimony (Oxide) - Borates Asbestos - Calcium Carbonate Attapulgite - Diatomite Ball Clay - Dolomite Barite - Feldspar Bauxite (and Alumina) - Fire Clay Fluorspar - Pyrophyllite Fuller's Earth - Rare Earths Graphite - Salt Gypsum - Sand and Gravel Kaolin - Silica Sand Kyanite - Soda Ash Limestone - Sodium Sulfate Magnesite - Spodumene (Lithium) Magnetite - Sulfur Mica - Talc Nepheline Syenite - Titanium Dioxide Perlite - Vermiculite Phosphates - Wollastonite Potash - Zeolites Pumice There is some overlapping. Fuller's Earth takes in some attapulgite, bentonite, and other minerals, depending on the market. Some would like to distinguish industrial minerals by the market emphasis they receive compared to fuels, metallics, and precious metals. But even there, strict logic fails. Some industrial minerals are commodities. They are sold on a price basis against industry product specs, usually in large volumes. Phosphate rock, potash, sulfur, salt, soda ash, and other materials fit this category. Some are almost custom-designed for end-use and meet performance specs. These are sometimes called functional or specialty industrial minerals. Examples of these are ground calcium carbonate, water-washed kaolin, cosmetic grade talc, filtration grades of diatomite, perlite, and vermiculite. To determine prospects for the decade ahead, regardless of our

Jan 8, 1984