Mine planning for aggregate operations, even 30 years ago, was fairly primitive. Aerial photographs provided a platform from which a map could be drawn, but plans were no more complicated than pen on Mylar. “Everything was analog. As a mine developed, we would use overlays of Mylar to create models of the mine by year,” says Rob Vogel, founding partner of Q4 Impact Group.
For a greenfield site, a geologist would go to the county courthouse for a paper property map, says Jim Stroud, vice president of Subhorizon Geologic Resources. “Everything was hand-drawn,” he adds. “The first year I had a computer to work with in planning was 1992. We began to use Excel and then AutoCAD through the 1990s.”
Vogel calls the advent of using spreadsheets “Phase II” in the evolution of mine planning technology. “Aggregate producers were more concerned with generating volume by year, and made all of their calculations by hand. When spreadsheet programs came into use, it made the calculations a lot more efficient. We were able to more quickly and easily create different scenarios for production,” he says.
As the technology became more sophisticated, and online services were increasingly available, county parcel data was easier to find and use. “Most counties have parcel data, with zoning and all layers there to see – streets, creeks, boundaries – all online,” Stroud says. “Today, GIS is the way to go for exploration. You can look for, say, properties of 100 acres or more, with parcels zoned for heavy industry or allowed zoning classifications for mining. Then you can overlay the geology.”
Zoning and permitting are often a challenge for producers. Every county has different land use restrictions. “You need all the information you can get to make your point. If there is no technical reason to deny a special-use permit and rezoning, if you have addressed air, land, water, traffic studies, with all of the evidence, it becomes more difficult to turn down your requests,” Stroud adds.
Stroud and Vogel agree that today’s technology for mine planning is light years ahead of what was available even 10 years ago. And some, such as Google Earth, is free. As a preliminary platform to work into AutoCAD or other mine planning software, Google Earth easily takes planning to a high level of technology at a low cost.
One of the industry’s newest technological tools is the unmanned drone. According to Scott McTavish, solutions consultant for Kespry, Inc., 3D views from a drone’s high-resolution imagery provide an effective method to plan for development. Fight data is automatically uploaded to the cloud, then software auto-generates contour lines and overlays PDFs showing site-specific data. CAD and GIS data can be downloaded and put it into advanced mining software packages, he says.
An Evolution in Mine Planning
Scott McTavish is a solutions consultant for Kespry Inc. He is considered to be a pioneer in the drone space; before joining Kespry, McTavish formed one of the first UAV (unmanned aerial vehicle) surveying companies in the world. He also specializes in UAV surveying and business development. McTavish has degrees in geography and GIS from Western University.
Vice President of Subhorizon Geologic Resources, LLC, Jim Stroud is a licensed professional geologist. He started the company with his partner, Brett McLaurin, in 2013. Prior to that, he served as staff geologist, senior geologist, and manager of geological services for Vulcan Materials Co.’s Mideast Division. He has a bachelor’s degree in Geology from North Carolina State University.
Rob Vogel is the founding partner of Q4 Impact Group, which facilitates company efforts in best practices, core competencies, and bottom-line improvement. Previously, he served as president of Vulcan Materials Co.’s Midwest Division. He has a bachelor’s degree in mining engineering from the Colorado School of Mines and an MBA from the University of Chicago.
Voices of Experience
Metal miners have understood the intricacies of mine planning, such as grade control, for longer than aggregate producers, says Rob Vogel, founding partner of Q4 Impact Group. “Many aggregate companies operated more by the seat of their pants. Their resource was homogenous, and they were more concerned with producing volumes of material,” he says.
Thirty years ago, as spreadsheet software became more available and PCs developed after main frame computers, mining engineers were able to put dedicated computing to use as they planned for mine development. “At that time, aggregate producers typically stayed where they were. They might have created analog block models to plan for production by year, but that was about it,” Vogel explains.
Once producers began to explore technology to help their operations, their emphasis was more on fleet optimization and operational efficiencies. “Permitting processes relied more on life-of-mine planning. The planning process still didn’t require sophistication; producers needed a way to address land, air, water, vibration, noise, and the reclamation concerns,” Vogel says. “But they really didn’t dedicate much planning for control of the grade, and so on, even then.”
During the 2000s, larger aggregate companies began to take advantage of the same software that the metal mines were using to develop plans for the life of the mine, creating block models on AutoCAD or similar programs.
“But the industry has consolidated a great deal, and Millennial employees are fully comfortable with technology. We’re light years away from early computing, and it’s become cheaper and cheaper to use. Now we have LIDAR, and we’re generating surface data in the cloud – with billions of points; we can easily apply finite element analysis to rock mechanics. Today, we don’t just plan for volume,” Vogel says. “As an industry, we are all becoming more sophisticated in all of our planning from choosing a site to reclamation.”
During exploration, a producer should always work with an experienced geologist to determine major rock types and structures in a proposed mine site, says Jim Stroud, vice president of Subhorizon Geologic Resources, LLC. Most exploration techniques haven’t changed drastically. However, drilling and various geophysics methods are much more efficient.
“Prior to mining on any site, the producer must determine such factors as how deep is the rock? This study is important because you need to know where the shallowest overburden is and the best quality rock; you’ll want to mine there. Where is the deepest overburden? You’ll want to put your plant there,” he says. “In sand and gravel, what is the gradation and quality of the material? Where is the deposit? You want to mine where the thickest amount of material is, and put the plant on the thinnest part of the deposit.”
Stroud says that geologists need to map all faults, joints, foliation, and bedding planes, as well as any surface water or groundwater. These types of discontinuity trends should be mapped prior to the original mine plan and incorporated into it, especially regarding face orientations and bench configurations.
“Many rockfalls or slides in quarries are the result of lack of planning and not integrating the geologic structure into the mine plans,” he notes. “As key geologic structures are exposed in existing operations, face orientations can then be changed.” Surface water can be routed around the quarry and groundwater pressures can be relieved utilizing toe drains in key areas.
Stroud says that some geologists still employ “old school” methods and tools, such as a Brunton compass, to determine point bases and bedding planes. But GPS with lasers are now available, as well as drones to reproduce topographic maps, and software programs are available to help geologists evaluate the safest face orientation relative to discontinuities, simulate rockfalls, and calculate factors of safety.
Drones provide a safer and more accurate approach to gaining surveys, topographics, and volumetrics in mine planning. They reduce the need for some of the physical aspects of exploration and mine planning and provide low-cost, accurate survey data, says Scott McTavish, Solutions Consultant for Kespry Inc.
“While each drone solution is different for mine planning, in general, drones ascend to a predetermined height and autonomously follow predetermined flight paths that the producer has generated from mapping software. Taking photos at regular intervals, the drone stores the coordinates, photo ID, timing, and camera angle for each shot. From there, Kespry’s Automated Drone System transmits all of the data wirelessly to the Kespry Cloud,” McTavish says. “The producer can log into their account online, and access topographical information, volumetrics for stockpile measurement, and more – and can visualize all of the spatial data in 3D.”
McTavish says that drones provide useful, visual information to use in exploration, zoning, and permitting, mapping out roads, streams, lakes, and general topography. When used with GIS and advanced mining software, the data from automated drones can help with mine plan factors such as pit development, determining access roads, and planning for reclamation.
Traditional, manned aerial surveys have been cost prohibitive in the past. For this reason, many producers may only do an aerial survey once every year or two, while using ground-based surveyors in between.
“There are applications for drones throughout the life of the mine. When used on a frequent basis, the resolution is so high with the drone’s imaging that sending the drone on the same flight path over and over allows the producer to compare changes in slopes and walls to track their stability,” McTavish says. “Automated drones can give producers the flexibility and freedom to collect data whenever they want.”