Exploration equipment review.
The level of sample recovery in mineral exploration is critical in establishing the location and quality of a deposit. Poor sample recovery, or lost samples, can make an exploration team's task impossible.
Golconda Resources Ltd. has been using a Bulroc reverse-circulation hammer on a project in California with surprising results. Working with standard hammers in fractured rock on the Star City claim, the company had recovery rates on a 1.5-m sample interval from 0 to 5% with lost sample intervals accounting for 10-25% of each hole.
In an attempt to improve sample recovery, Golconda acquired a Bulroc reverse-circulation hammer from Canterra Equipment of Calgary. Project geologist Cal Herron said the Bulroc RC hammer resulted in vastly improved sample recovery because of its center sample-recovery or dual-wall drilling design. The Bulroc (UK) Ltd. RC down-the-hole hammer ensures sample purity by collecting the sample at the source and passing it directly through the contamination-free hammer body, rather than around the outside of the unit where the sample can easily become contaminated or lost in fissures.
Working alongside holes drilled with the standard RC hammer, Golconda found that the Bulroc produced "amazing results." From a total of 12 holes, more than 95% of the samples recovered had a recovery rate of better than 50%, according to Cal Herron. In addition, not one sample taken at the same 1.5-m interval depth was lost. Circle (01)
Putting one's drillholes where one wants them is a perennial problem for explorationists. Often poor ground conditions and natural bedding planes cause drillholes to stray from the planned position, and they have to be wedged back on course, an expensive and time-consuming procedure.
Devico, a Norwegian company, is offering its drilling expertise to drilling firms worldwide. Its main product is an innovative down-the-hole tool for diamond core-drilling with directional control, the Vic drill-head. The unit has undergone extensive trials in Scandinavia over the past year, both in site investigations for various tunnel projects, and for core-sample drilling at the Viscaria mine in Sweden.
The tool consists of a double-tube drilling unit attached to a the regular drill string. The inner tube with the bit is angled relative to the outside tube by one or two eccentric bearings. The outer tube is first oriented into the correct position with an internal inclinometer that signals its position to surface and then locks against the drillhole wall by a rubber packer at the back of the unit that is inflated by the drilling fluid pressure.
Once locked in position, drilling commences with a bit deviation of up to 1.5 /m in the desired direction. The tool makes a 56-mm-dia hole and gives a 30-mm core. Circle (02)
As important as being able to place your holes where you want them is accurate borehole survey. A new borehole survey instrument, the Reflex Maxibor, is an evolution of the Fotobor but eliminates the use of film and film processing techniques. Results are available immediately at the rig.
The instrument measures the bending of the probe in the drillhole using optical measurement of angle and distance. The instrument is encased in steel rods, each having threaded couplings and a double O-ring seal. Assembled, this forms a sealed self-contained unit with a maximum outside diameter of only 45 mm.
Reflector rings are placed within the probe at 1.5-or 3-m intervals from the main lens. The shorter interval is used where hole curvature is expected to be less than 100-m radius. A liquid level-sensor is mounted in line with the reflector rings and defines the vertical plane. The optics are based on a light source directed at and reflected by the rings. The reflected image is recorded by a video camera and passed to a real-time analyzer that employs pattern-recognition techniques to extract deviation data and store it directly in the on-board memory.
When running a survey, the Maxibor is first synchronized with the portable field computer. The probe assembly is then run down the hole on rods or wireline. It is stopped at 1.5-or 3-m intervals and each station is keyed into the computer. The procedure can also be repeated as the instrument is withdrawn to surface.
On completion of the survey, the Maxibor is reconnected to the field computer and stored data is downloaded for display without further processing. These immediate results are a summary of deviation data, but when computer and plotter are connected a full set of survey results can be presented. Maxibor software will link with many commercial programs for borehole investigation.
Reflex Instrument AB claims the Maxibor eliminates the inaccuracy of the compass, pendulum, and orientating rods used by other survey systems, and can survey a borehole relative to the collar to an accuracy of 1:1,000. Circle (03)
Aerodat's Integrated Survey provides the full range of hardware and software for the collection, analysis, and presentation of geophysical data. The results, according to Aerodat, are as accurate as ground horizontal-loop electro-magnetic (HLEM) profiles. The advantage is in the helicopter-borne electromagnetic (HEM) surveys' ability to be employed in harsh environments, elimination of measurement noise created by transmitter-receiver orientations, dense sample data, and avoiding line cutting in advance of the survey.
The key to the HEM-survey system is a 7-m Kevlar "bird" that contains two coil pairs at each end. Horizontal coplanar coils operate at 4,175 hz and 33,000 hz. The vertical pair of coaxial coils operate at 935 hz and 4,600 hz. With this "bird," Aerodat can collect data at a 0.1-sec scan rate from a helicopter flying at 50 m/sec. The system measures in-phase and quadrature responses at each frequency in ppm of the primary-transmitted field.
The high-data collection rate of the HEM is processed using on-line inversion techniques for initial analysis. It avoids suppressing data in the interest of minimizing noise. A higher transmitted dipole increases the geological signal relative to that of noise.
Real-Time Imaging (RTI) was developed by Aerodat and Geopac for presentation of the data. Two-dimensional color maps and line drawings can be generated using this hardware/software combination. The mouse-based, menu-driven system makes it easy to manipulate images to show up to four sets of data simultaneously. RTI may be used independently or interfaced with other Geopac software packages for completely professional in-house data compilation. Circle (04)
The introduction of the JKS Boyles Super 300 has added a new dimension to the JKS 300 line. In addition to the light-weight and high-performance qualities of the 300 line, the Super 300 adds a design to maximize safety and simplicity. It has drilling-depth capabilities of 1,600-ft AQ, 1,200-ft BQ, or 800-ft NQ.
This new drill is made up of two main components. The power plant is a four-cylinder, 70-hp engine driving a hydraulically powered JKS Brahma pump. On this same component is the control panel, with what JKS claims are some of the simplest and widest range of controls for down-the-hole operations. The power-plant unit weighs 1,555 lb, including the motor.
The second unit is the mast-mounted drill. Fully extended, the mast is 17 ft high. For transport, this can be collapsed to 8 ft. The drill chuck is a JKS "fast-action" self-centering design. The wireline winch has a 1,600-ft capacity for 3/16-in. cable. An optional accessory is the heavy-duty wireline winch with a capacity for 2,500 ft of 3/16-in. WL cable. There is a standard 44-in. feed stroke hydraulic cylinder that can up to deliver 12,000 lb of pushing and 8,500 lb of pullback force.
The two units could be transported together, or independently, to minimize downtime for teardown and re-assembly. Each major component can be further broken down to suit any transportation requirement.
Optional accessories include a hydraulic holding clamp, a tachmeter for the wireline head, drill-mast skid, drill-mast base plate, and ball-type rod puller. Circle (05)
The Brunton Co. has introduced a 10-pocket vest designed for field work. The Professional Series vest is backed with what Burton believes to be the first 5-yr warranty on any type of field garments. The multi-pocket vest is available in sizes S, M, L, and XL; it is designed for use by geologists, surveyors, prospectors, etc.
All its vests feature two large hand pockets with retainer seams, two front-expansion pockets, a full-back storage pocket with side snaps, inside pockets with Velcro seals, and two accessory pockets.
Constructed of 10-oz cotton duck with reinforced stitching throughout the entire garment, these vests will withstand the toughest field conditions. All materials are water repellent and mildew resistant.
Brunton Co. is famous for its pocket transits, which it has made for the past 90 years. Circle (06)
Gemcom's PC-Xplor system stores, manipulates, analyzes, and displays all types of exploration data. It allows a wide range of data-entry techniques and reporting. And, perhaps most usefully, its modular design can be continually expanded to suit the operators needs. The modular design allows integration with other Gemcom software packages, so that a deposit can be monitored and evaluated from initial location through mine design.
The PC-Xplor database can be as simple or complex as a job requires. Data on drillholes, mapping, geochemical, or polygon information may be entered into standard templates or user-defined ones. In addition to manual data-entry, PC-Xplor will read ASCII files into newly created databases. Comprehensive text editors allow reformatting and reorganization to incorporate new project-developments.
There are a variety of methods for manipulation available through PC-Xplor. In addition to the database manipulation functions, histograms and scattergrams may be generated to identify trends. Modeling functions will help develop semi-variograms. Data can be presented on grids and contours to identify sample distribution or anomalous zones. Many statistical and geostatistical functions are included for these purposes, including interactive regression analysis, interactive variogram-model fitting, inverse-distance interpolation, kriging, three-dimensional surface fitting, and contour preparation.
PC-Xplor can then export assay data in three ways: * using the included QuickPlot system, it can be used to present overlain charts taken from a series of data sets, prepare drillhole plans, extract color-coded data subsets, or overlay contour plots produced from gridded-point data; * export graphics to AutoCAD for complete graphics flexibility; and * export drillhole sections to Gemcom's GeoModel for interactive interpretation and polygon reserves. Circle (07)
Christensen Mining Products's research department recently tested various diamond combinations with a new matrix. This cumulated with 14 successful field tests of the latest in matrix and diamond combinations, the Gold bit. Tests were conducted in a variety of U.S. geological conditions: chert in northern New York state, hard dolomite in Tennessee, fine-grain granite in southern Montana, quartz in central Nevada, to schist with massive quartz veins in Alaska. These tests showed an increase in hard-rock drilling production of 15-20%.
In ultra-hard formations, currently available diamond-impregnated bits become polished and penetration rates quickly fall off until the bit is simply spinning on the bottom. Christensen's new Gold diamond-impregnated bit has been especially designed to meet the challenges of ultra-hard, dense, consolidated, non-abrasive formations.
The secret to this faster penetrating, longer lasting Gold bit is the unique combination of diamonds and a new matrix design, The Gold bit's matrix is designed to continually expose the diamonds, so they can sharpen, not polish, themselves when slowly breaking down. Circle (08)
The GPS Nav 1000 Pro, at $3,750, is one of the least expensive hand-held GPS (global positioning system of satellites) receivers currently available, according to Magellan Systems Corp. The manufacturer points out that "Whether the task at hand is to systematically find a deposit in a remote location, to subsequently return to the site, or to later manage it, the GPS Nav 1000 Pro offers key navigational assistance. Real cost savings are experienced through the Nav 1000 Pro's ability to replace a surveying team in determining preliminary calculations and positions."
The uses of the Nav 1000 Pro include establishing survey control in remote, unmarked areas in the field, plotting coordinates, and storing coordinates. Positions are provided in either latitude and longitude or in UTM formats. In its autonomous mode, position accuracies will fall within a 25-m range. Setting the unit to average positions, this accuracy improves to 10m. Also, if greater accuracy is desired, two units may be used in differential mode to provide 1 to 10 m of positioning accuracy.
The Nav 1000 Pro is capable of storing up to 200 position fixes in its data buffer. These fixes may then be downloaded through its RS232 port into a data logger or laptop computer. Magellan's software allows data to be reformatted and plotted.
The unit weighs only 30 oz, and is shock resistant and waterproof. Although light and versatile enough for hand-held travel, special adaptive hardware is available for mounting on a range pole, tripod, or vehicle. Circle (09)
The Metal Analysis Probe (MAP) III Portable X-Ray Fluorescence Analyzer, from Scitec, allows the prospector-explorationist to have on-site, real-time analyses performed for assessment work. No sample preparation is required, and each analysis takes an average of one minute.
MAP III is a hand-held, multi-element probe that performs quantitative analyses for silver; base metals; and trace elements, including those elements associated with gold. The in-situ analysis can be performed in drillholes up to 250 ft deep. Combining MAP with Rockware's Logger graphic drillhole log software, on-site graphic, geologic, alteration, mineralization, and multi-element analysis of the drillhole log can be generated within minutes of the last sample being collected.
MAP III has applications throughout the phases of mine development and operation. During the exploration/drilling phase, it saves time, labor, and money by providing real-time analysis to define mineralized zones quickly. In the mining phase, MAP III can aid in ore control, identifying ore that has overlooked and sent to waste, or waste that has mistakenly entered the mill. For the metallurgist, MAP can help in process control.
Jaba Inc. will provide these MAP III analytical services at exploration, drilling, and mining sites for companies that occasionally require the functions of MAP III, but do not wish to purchase it. Circle (10)
Geomath Inc. writes geostatistical and modeling software for exploration and mine planning. Its main product is the GDM System, a line of many software packages. Three programs, the GDM Drillhole System, Geogrid, and Seccad, are part of this larger system, which is designed to assist in each stage of mine development from initial deposit definition to final mine planning.
The GDM Drillhole System is dedicated to the management and display of drillhole data. Its main purpose is to generate high-quality graphics for logs, base maps, cross sections, and three-dimensional views. The Drillhole Survey System will display point and curve data, in addition to the drillholes. An array of compositing techniques are offered to identify the best intercepts and average the data by regular bench intervals. The system can handle all types of down-the-hole data: sample values, alpha codes for rock types and alterations, numeric fields for geochemical assays, geophysical logs, geotechnical data, and text fields for descriptions. The GDM Drillhole System comes in two different versions: * The base module groups the functions to load drillhole data; calculate down-hole coordinates; and display drillholes by strip logs, base maps, and sections. * The full module adds compositing capabilities to these functions. It contains gridding programs as well.
Geogrid may be used as stand-alone software or as part of the GDM System for two-dimensional mapping. It employs sophisticated contouring techniques, capable of handling faults, trends, and anisotropies. Geogrid also comes in two forms: * The base package includes the gridding and contouring functions, but has limited data-management capabilities. It is meant as an inexpensive way of using sophisticated gridding. * The full package adds the complete environment to two-dimensional mapping, as well as three-dimensional surface plotting.
Seccad is an application program for computing mining reserves from cross sections. Interactive, color-graphic functions allows optimization of stopes, pits, and reserve outlines; corresponding reserves are automatically calculated. Seccad displays geologic cross-sections (including hole traces, geologic contacts, and mine-plan features), then calculates reserves from mine-plan layouts. Mine designs may be interactively modified with reserves automatically recalculated, until an optimum design is found. Optimized stopes and pits can then be stored for reporting in other GDM programs.
The GDM System is not the only product line from Geomath. An example is Geores, a package containing three main geostatistical functions: variogram calculation, kriging, and volumetric or reserve reporting. Both two- and three-dimensional statistical calculations can be made with Geores. Circle (11)
Minesoft offers engineering software for solving real world problems. Packages include applications for database, statistics, modeling, graphics, pit design, geostatistics, and Lerchs-Grossman 3-D optimizer.
TechBase is a flexible, integrated database management system. The modeling package has the ability to estimate or calculate spatial statistics from two- or three-dimensional data values, and it incorporates value estimation techniques for triangulation, trend surface, inverse distance, and kriging algorithms. Circle (12)
IN-SEAM SEISMIC PROGRAM
When mining with longwall methods, it is important to avoid geologic faults. If the fault is discovered while mining, it is far too late. The time to search for faults is during the longwall planning stage.
Using the in-seam seismic program from Mining and Construction Technologies, Inc., can help avoid these unexpected faults. The in-seam seismic programs for coal can provide long-range predictions of all relevant faults, as well as proof of uninterrupted reserves. This information can provide security and confidence in long-range mine plans.
The company has shot over 1,000 surveys worldwide, and it is currently completing over 150 surveys per year. Circle (13)
Bondar-Clegg has built its reputation on providing accuracy in its mineral testing. For example, when samples are analyzed for elements such as Hg and As, or are high in clays, drying temperatures are held to less the 55[degree] C. Higher temperatures would drive off these elements and the water of crystallization, giving inaccurate results. The process takes longer, but gives better results.
Each sample is custom fluxed. In order to produce an effective fusion and complete collection of gold, it may be necessary to adjust the flux for each individual sample. Time it taken to meet this important requirement.
Quality control is strict for each step in the laboratory process, from sample preparation to data presentation. Circle (14)
Longyear has a long reputation as a complete source of drilling equipment. Longyear impregnated diamond bits, for example, are designed for high penetration rates even in ultra-hard formations where they offer greater production per man-hour than conventional bits. Longyear heat-treated Q wireline drill rods undergo a series of 12 quality checks to insure that every single rod has consistent strength. Longyear guarantees such rods as free of defects, and backs this up with essential features such as precision manufacturing and induction-hardened ends. When you purchase Longyear equipment says the company, you are backed by the most complete service network in the industry. Circle (15)
BHP Engineering's geosensing can accurately map what lies below the surface so that planning engineers can work with greater confidence.
BHP offers in-seam seismic services to detect disturbances in coal seams. Cross-hole seismic tomography can detect geologic features between boreholes. Ground probing radar is available for shallow investigations from the surface or underground. High-resolution surface seismics are also offered. Image enhancement, using advanced processing techniques, will improve data. Circle (16)
Drilling often does not produce a straight hole. By their nature, drill bits tend to deviate. The degree that they deviate depends on bit type, hole size, rock strata, and the depth of the formation drilled. A steeply dipping formation, for example, can aggravate the problem of drilling a straight hole.
Christensen Boyles' directional drilling group used the Navi-Drill/Welnav down-hole motor and deflection shoe to achieve the "straightest hole pilot ever drilled in Australia," out of alignment just 138 mm over 600 vertical m.
The hole can be surveyed at the end of every 20-ft core interval. If the hole is out of tolerance, the Navi-Drill down-hole motor can be employed to correct the course of the hole. The Welnav steering tool can be wirelined into the hole and engaged behind the down-hole motor, giving constant surface readout data during any hole correcting drilling.
The deflection shoe has been used as a down-hole correction device with good results on both vertical and angled holes (see E&MJ July 1988, p48). Circle (17)
PHOTO : Defining the vertical plane
PHOTO : Establishing the position of a ring relative to the vertical plane.
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|Publication:||E&MJ - Engineering & Mining Journal|
|Date:||Jul 1, 1990|
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