Mine Haulage
Mine Haulage
Mine Haulage
In this unit, you will learn about mine haulage systems used to transport ore/waste, men, and materials within a mine.
After completing this unit, you should be able to: List the major types of haulage systems Explain the purpose of : Scrapers Slushers Scooptrams Locomotives Ore Cars Explain the ore circuit in a mine Explain the ore circuit in an open pit
Ore/Waste Handling
Early methods of underground haulage included carrying material in sacks, baskets, or other containers, sleds, wheelbarrows, to cars running on a track.
At first ore cars were pushed by hand, later pulled by ponies, and horses
The first electric loco was used in 1882. A gasoline or diesel engine drive may be used instead of electricity
include conveyors, trucks, trains, and Today, haulage methods aerial tramways. Bulk solid transport of solids in pipelines is used for coal and other materials
Principles of Loading
After material has been broken, it must be loaded on some type of conveyance system to be removed. The following are the most common methods :
a) This is a typical person operated shovel. The shovel is pushed into the pile and then lifted. Most mechanical power and hydraulic shovels use this action.
Hand shovelling underground is called "playing the banjo". In general, 1 shoveler can move about 1 ton 100 ft. in 2.5 hours. A shoveler can handle about 17 to 20 tons per shift.
Principles of Loading
b) Instead of pushing the shovel into the pile it can be pulled. Most backhoes and draglines use this action.
Principles of Loading
c) The clamshell action is often used in shaft sinking. It digs from the top down.
Principles of Loading
d) The slusher or scraper bucket is similiar to a garden hose. The bucket is pulled towards the hoist.
Mucking Machine
i) A mucking machine runs on compressed air and uses the overhead cast type of loading. It is necessary to have an ore car either close or attached to the machine, so the material cast from the bucket will land in the ore car.
Slusher
The slusher or scraper system often used in underground loading, Slusher work is divided into 3 main classes: for loading cars at the face of drifts, crosscuts, tunnels and stopes, where material transported a short distance and the ore is pulled into an ore car. for moving ore from the face to ore cars some distance away. for moving ore to chutes or ore passes which lead down to a main haulage level
Principles of Loading
e) After a bucket is loaded it has to be hoisted, positioned, and dumped. Most power shovels hoist the bucket and swing to a dumping position
Principles of Loading
) A conveyor system is often used in coal loading. A gathering lip or pan is mounted on the end of a conveyor belt. The pan or lip has gathering arms or some type of rotating wheel or chain attached to it which gathers, scrapes, or pushes the broken material onto the conveyor belt.
Principles of Loading
g) A slusher system is often used underground. Ore is fed to the slusher lane through drawpoints. The material is scraped to the loading point
and loaded by gravity.
Principles of Loading
h) A recent development has been the LHD - Load-HaulDump unit. This unit loads a large bucket and lifts it a short distance and then carries it to a dump point. Generally these machines are powered with diesel engines and have great flexibility and versatility. Another term for LHD removal is "trackless mining".
Mucking Machine
i) A mucking machine runs on compressed air and uses the overhead cast type of loading. It is necessary to have an ore car either close or attached to the machine, so the material cast from the bucket will land in the ore car.
Yes
Production < 5000tpd -Yes ----- Production < 2500 tpd ----Yes Yes Ramp Haulage by Truck No ---Orebody < 300m deep ---- No ---- Inclined Belt Conveyor
MATERIALS HANDLING
In cyclic operations, the two principal operations are loading and haulage with hoisting an optional third. In continuous operations, where machines combine the breakage and handling functions, cutting, drilling and blasting are eliminated, and extraction and loading are performed in a single operation or function (excavation) e.g. bucket wheel excavator, auger, highwall mines, continuous miner, boring machine. Materials handling in modern mechanized mining is equipment oriented. Unit operations are characterized by and sometimes identified with the equipment that performs them. Thus field terminology refers to a mining shovel, stripping dragline or coal loader.
From time to time the mining engineer is faced with the necessity to make a haulage study to determine not only the most suitable method of hauling materials, but also the most effective and economical type of equipment to use for the operation.
Transported and dumped down an orepass into chutes on the level below.
A train hauls the muck from the chute to a main orepass where it enters a skip and is hoisted to surface. Several main orepasses can be used throughout the mine.
Ore Transportation
Step 1 - From the Stope
After the ore is blasted, it is removed from the stope. Most mines today use LHD or scooptrams to move the muck to centralized chute systems, which lead to levels below. Some mines use trucks, conveyor belts, pneumatic, or hydraulic systems to move the ore directly to surface
Ore Transportation
Ore Transportation
Step 3 - From the Level
Ore in the chutes is usually loaded into ore cars and hauled by an electric loco to a centralized orepass. Tramming is the moving of ore from chutes to a central orepass. Ore car used underground range from 1/2 ton to 30 ton capacity. Cars are pulled by locomotives powered by electricity, diesel engine, or compressed air. Electricity can be supplied by an overhead trolley system or by their own batteries
Ore Transportation
Ore Transportation
Ore Transportation
Step 6 - Skip
Skips are usually automatically selfdumping. A double drum hoist is used for skips. As one drum is wound the other is unwound, so when one skip is hoisted the other one is lowered into the mine.
Ore Passes
Mines take advantage of gravity to collect broken ore by means of ore passes. The ore passes are raises driven by drill and blast or raisebored. While ore passes are most commonly used for underground mining. Long raises are also employed as waste passes to drop quarried rock for cemented rock fill (CRF) from surface directly to the mining horizons. Ore passes often lead to an underground storage bin to provide surge capacity in the ore stream. In turn, the ore is normally drawn off the bottom of the bin into a chute
In bad ground, ore passes are often lined with concrete. In many cases, the concrete is faced with a high strength steel liner that also provides the formwork that is required to pour the concrete.
The steel lined ore pass has proven itself worldwide; however, the high cost and time required often make this design impractical.
A circular ore pass is more stable than a square or rectangular ore pass. The latter invites arching on the sides and stress concentration at the corners. The most stable ore pass is a circular raisebored hole; however, this type of pass has two disadvantages. The first is the problem of placing ground support in the raise and the second is the fact that a smooth circular raise is more prone to hang-ups than a rectangular raise that has been drilled and blasted. In highly stressed, burst prone ground, an ore pass usually has to be raisebored for safety reasons.
Bins
Underground bins are required to provide surge capacity to the ore stream. In the past, small mines simply slashed out an ore pass between levels to provide a bin. Today, most underground bins stand vertical and have a circular cross section. Larger bins are built with the bottom coned to inhibit rat holing of the ore. In some cases, liners are provided in the cone section to improve ore flow. Until recently, the maximum practical underground bin diameter was approximately 28 feet.
Chutes
Chutes are inclined steel troughs used for transferring shot rock. Near vertical chutes are covered on four sides and equipped with an access door. Inclined chutes are often left open on top to facilitate clearing blockages. The chute width should never be less than three times the size of the largest lump to be free running. Chute inclination in most operating mines varies between 37 and 40 degrees. Steeper chutes may require control chains to stem the muck flow
Chutes
MATERIAL PROPERTIES
Bank: Usually applied to weights or volumes of materials. The bankweight or bank-volume of a material refers to material in its natural state before disturbance. It is often referred to as "in-place" or "in-situ" material. A unit volume is referred to as bank cubic yard (bcy) or bank cubic meter (Bm3). Loose: Material which is in a loose, broken or blasted state or material that has been excavated or loaded. A unit volume is referred to as loose cubic yard (Lcy) or loose cubic meter (Lm3) Swell: Rocks or Soils increase in volume when they are excavated or blasted because soil or rock grains are loosened during excavation and air fills the void spaces created. Consequently, a unit volume of soil or rock in the bank condition will occupy more than one unit volume after excavation. This phenomenon is called swell.
a) Mobile Bulk Handlers - trucks, shuttle cars, ram cars b) Mobile Excavators - dozers, tractor scrapers, FEL c) Transitional Excavators - shovels, draglines, clamshells, muckers, cutters, loaders d) Integrated Excavators - boring machines, continuous miners, BWE dredges, longwalls e) Intermediate Handlers - railroads, hoists, tramways f) Fixed Handlers - belt, flight, spiral conveyors
TRUCK HAULAGE
In handling earth, aggregate rock, ore, coal and other materials, trucks serve one purpose. They are hauling units which, because of their high speeds when operating on suitable roads, have high capacities and provide relatively low hauling costs. They provide a high degree of flexibility as the number in service may be decreased or increased easily to permit modifications in the total hauling capacity of a fleet.
1. Diesel Electric - most prevalent because they can be adapted to any track gauge and are available in all sizes from small switch engines to large freight haulers. 2. Trolley Electric - have a top mounted pantograph or a side mounted collector to receive power provided by an electrified wire. b. voltages: 250 V and 500 V
c. Size range: 2 - 50 tons.
Haulage
Types of Rail Cars a. Side dump - more versatile and usually with capacities that range from 30 yd3 to 50 yd3. employed in hard rock mines and metal mines. can dump on either side b. Bottom dump more prevalent in coal mines
fast unloading
higher maintenance costs. c. Rotary dumping machines which turn over the rail cars for quick dumping of ore.
d. Rocker type
Conveyors
Underground hard rock mines use belt conveyors for lateral and inclined ore transfer; however, belt conveyors are not as popular as they are for similar surface applications. Belt conveyors for underground service usually are designed more rugged and operate at slower speeds than a comparable overland conveyor. Hard rock mine belt conveyors normally require the ore to be crushed before it is conveyed or at least broken enough to pass through a grizzly opening. The finer the ore is crushed, the longer the belt life, the more reliable the system, and the lower the operating cost.