This review gives information about surface and underground mine haul roads. Topics discussed include haul road design, maintenance, and health and safety. Information about dust control and soil stabilization product suppliers is also given.
This quote from the South African CSIR website best justifies this State-of-the-Art Review:
Principal, but often neglected components of any mining or forestry operation are the haul roads. These roads are often designed with little expertise, resulting in expensive maintenance requirements and high vehicle operating costs. Truck haulage costs can amount to between 30 and 50 per cent of total surface mining costs and up to 60 per cent of total forestry operation costs. The savings from appropriate design, construction and maintenance of haulage roads and utilization of the most suitable materials can thus be significant.
Mine haulage costs at open pit mines may represent 50% of the mining cost and sometimes as much as 25% of the total costs, which include processing, marketing, and overheads.
The following are the best manuals I came across on the design, operation, and use of mine access and haul roads:
While it does not specifically address mine access roads, the California Highway Design Manual contains considerable useful technical information for anyone designing, maintaining, or using a mine access road.
A fascinating survey of a proposed mine access road and its physical impacts is the study for the Tulsequah Chief Mine Access Road.
Another overview of a long and important mine access road in Alaska is the update on the True North Project Haul Road.
Attlin to Tulsequah Chief Mine, British Columbia, Canada:
Proposed Haul Road. (From Skytruth)
The Michigan guidelines for mine traffic control include a nice set of practical points.
HAUL ROAD DESIGN
A thesis from the University of Alberta examines new and better haul road designs for these large and expensive trucks. Here is the abstract from this thesis (slightly edited to improve clarity based on my reading of the remainder of the thesis):
Large haul trucks are used at surface mines in Canada thus requiring better haul roads. The mines use empirical design methods, which may not result in optimum road design. A road design method based on resilient modulus results in better haul road designs than the CBR-based method. Numerical modeling done to analyze the effect of material modulus, layer thickness and tire interaction on strain bulbs in a haul road, showed that putting the stiffest layer at the top results in least vertical strain-hence improved road performance and reduced truck wear and tear. Coal mines located adjacent to coal-fired electric power plants produce fly ash as a waste by-product. Tests of fly ash, kiln dust and aggregate mixes proved that fly ash significantly improves the strength and bearing capacity of aggregates thus enabling use of thinner layers for road construction.
A functional mine haul road needs a reliable wearing course to avoid damage to the mine trucks. The wrong wearing course material reduces safety, reduces truck efficiency, and increases road and vehicle maintenance. A paper from professors at the University of Pretoria, South Africa, establishes guidelines for selecting materials for unpaved mine haul roads. Without going into the details, suffice it to say that the professors document guidelines for selection of wearing course materials based on the material's density, dust ratio (a geotechnical parameter I have not previously encountered, but it is intuitively obvious), Atterberg Limits, CBR, and particle size distribution. Even if you never use the complex system they set up, I recommend the table of haul road performance characteristics and the rating of severity of defects and the basis for deciding when to undertake repair and establishing the nature of such repair.
Road Analysis Control (RAC) is an information product that allows the customer to monitor haul road conditions and improve large mining truck performance, productivity and safety while lowering repair, maintenance costs and downtime. Integrated with the Vital Information Management System (VIMSŪ), RAC provides real time feedback to the operator about haul road conditions which are detrimental to cycle times and power train, frame, suspension components and tires. Through the VIMS message center, two levels of RAC events alert the operator to places in the haul road, which require attention, both from the standpoint of truck operation and support equipment. When used with a telemetry system like Caterpillar's VIMS wireless, By monitoring this data, mines will be able to identify and attend to haul road sections affecting cycle times and component life.
Onemine appears to a have a significant number mine haul road design technical articles available, however you must subscribe to access these papers.
KEEPING UNDERGROUND ROADS SMOOTH
The first thing that caught my attention about the PAUS Dinting Machine PSF 200, is the word "dinting" attached to its name. According to The Free Dictionary, dinting is the action of forcibly putting a dent into something. Together with the biggest mine in Russia - Norilsk Nikel - Hermann Paus Maschinenfabrik developed the PSF 200 to maintain underground supply routes.
In the past, a hydraulic hammer was used to loosen rutted road surfaces, which were then graded. This required two machines and proved inefficient. With the Paus PSF 200, the functions of "dinting" and "grading" is in one unit. Using a dinting-head made by the company Eickhoff, the Paus PSF 200 easily copes with hardened roadway surfaces up to 500 mm and rock hardness up to 80 MPA. To minimize dust, a sprinkler system is installed above the dinting-head. As the dinting machine loosens the rutted surface, a scraper blade fills in the ruts and levels the road. This sounds like a great solution and I'm surprised this isn't a machine you'd see at all mines, whether underground or not, since I'm sure well-maintained roads result in optimized vehicle speed and ultimately improved productivity.
UNPAVED ROAD MAINTENANCE
Although the reference I describe here does not deal with mines, I consider the topic and the treatment worthy of reference by the civil and geotechnical engineer and miner charged with constructing and maintaining unpaved access roads to and around mine sites.
I refer to Recommended Practice Manual-A Guideline to Maintenance and Service of Unpaved Roads published by the Choctawatchee, Pea, and Yellow Rivers Watershed Management Authority in February 2000. These places are in Alabama, in an area not much affected by mining. Rather they appear to have many unpaved roads and a continuous need to maintain and service them. The guidance includes extensive descriptions, guidelines, figures, and suggestions for good practice; all of which may be implemented with benefit by the average mine in most areas of the world.
Chapters deal with the road surface, ditches, culverts, outlet structures, bank stabilization, sediment and erosion control tools, aesthetics, and beavers. I quote from the Purpose Statement: "To provide a written manual of standard procedures which describe and illustrate cost-effective techniques and practices which can be used to enhance maintenance and stability of unpaved roads while reducing sedimentation and improving the quality of surface waters."
The text is readable, the guidance plain and sound, and the details practical. If this is your area of responsibility on a mine, may I recommend that you refer to this manual at the link given above.
A second major document on a related topic is Best Practices for the Design and Construction of Low Volume Roads published by the Department of Transportation Minnesota. Such road have an asphalt cover, but the ideas and procedures may also interest the mining community.
HEALTH AND SAFETY
At the MSHA site you will find a self guided tour on the safety of mine access and haul roads. The number of graphic pictures of vehicles and trucks run over, run down embankments, and tipped up because of poor mine road design, maintenance, or use, reminds us all of the criticality of this topic to cost-effective and safe mining.
A visually effective presentation is the Michigan Mine Safety and Health Program Guidelines for Traffic Control at Surface Mines.
See also the TechnoMine review on mine health and safety.
Computer codes to help in designing mine haul roads are found at sites including:
Sadly no one can "supply" a mine haul road; it was to be designed and constructed in situ. And it has to be maintained. The supplier most likely to be of interest is the one who can help control the dust from an unpaved road. Here are some such suppliers and information sources:
CBR Plus LLC. I particularly liked their brochure, including the soil chemistry lesson that explains why the product works, which can be found here.
Mega Corp has the trucks that do what I am most familiar with, namely spray vast quantities of water on the roads. How refreshing that always was in the hot deserts of my first construction site.
Midwest Industrial Supply, Inc has a well-stocked website with loads of information on and a wide range of products for conventional and other dust control methods in mining and other industries. I will go back to this site. They even have products for bike trails. They get my vote.
Soiltac Dust Control provides dust control materials to the US military in Iraq-interesting side aspect of operations in an undoubtedly dusty place.
Polo Citrus Australia has the prettiest website with "natural" dust control product for sale. Not quite what you expect from mining Australia. Worth taking a look at even if only to see their photo gallery.
Dust-A-Side is a South African-based company specializing in total dust control management systems for the mining industry. They have dust binding products and construction and maintenance programs to help you control your mine's dust.
Dustkill is a mid-west distributor of 100 percent agriculturally derived oils the cure, stabilize, control, and provide dust abatement for mine haul roads.
Road Material Stabilizers (Pty) Ltd. carries that fascinating South African (Pty) after its name. I once studied the law behind this, but forget the details. Regardless, they have a full line of soil stabilizers, binders, dust suppression and erosion control products.
RhinoSnot Soil Stabilizer. Who can resist a product with this name. They promote its use on mine tailings, landfills, and stockpile caps. And it is used in Afghanistan by the U.S. Marines. Actually the company is called Environmental Products & Applications, but that is ordinary!
The Martha Mine case history of dust control is interesting as an example of full-scale mine application and use.
The Foam Book is an odd website containing links to other site and publications on dust control and other foam technologies. But mine roads is hardly it's focus, so go here for general interest only.
The Dust Control Handbook covers dust control from all aspects of minerals processing industries; it is comprehensive.
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