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[...]... components of a drilling system: a, Drilling (source) b, Rod (transmitter) 29 Department of Surface mining English’s lecture for open pit mine speciality c, Bit (applicator) The three main components are related to the utilization of energy by the system in attacking rock in the following ways: a, The drilling is the prime mover, converting energy from its original from (fluid, electrical, pneumatic, or combustion... having a specific gravity of 3.0 and less, the necessary velocity is given by the equation: 13,300(S)D 3 / 2 V= (S − 1) Where: V is air velocity, in fpm S is specific gravity D is diameter of rock particles, in in The necessary compressed air requirement to achieve good hole cleaning is pound as follows: V(A − a ) Q= 144 Where: V is air velocity, in fpm A is area of hole cross section, in in2 a is area... 4 Can haulage steep adverse grades (up to about 40%) 5 Require material broken into fairly small pieces for good belt life Some of the principal factors affecting the cost of open pit mining are the size of the operation, the kind of material mined, and the distance it is moved As a rule, the cost per ton tends to decrease with increase production, large equipment (assuming it is run full time), decreasing... problems involved is needed to evaluate the result 1 Basic concepts Following are four distinct examples of mining and stripping schedules The first two are extreme cases used for illustrative purposes only (Declining stripping and increasing ratio method) a, Constant stripping ratio method: This method attempts to remove the waste at a rate approximated by the overall stripping method The working slope of... point of view is a compromise that removes the extreme conditions of the former two stripping methods outlined Equipment fleet size and labor requirements are relatively constant b, Phased mining sequence (Fig 5.4) In actual practice the best stripping sequence for a large orebody would be one in which the stripping rate was low initially and towards the end of the life of the mine This has the following... distribution of the values within that orebody Is the ore massive or scattered, bedded or disseminated, thick or thin? 2, The nature of the overburden to be moved Is it a hard dense rock, bedded rock (thin or thick), friable material, earth, sand, clay, march…? 3, The character and significance of geologic structure associated with the ore occurrence Are there water bearing formations with resulting... surface drainage is essential in measuring the availability and suitability of water for process and domestic use 11 Department of Surface mining English’s lecture for open pit mine speciality LESSON 4( 5 ) PIT PLANNING 4.1 Concepts of open pit mine planning An open pit mine is an excavation made in the earth’s surface for the purpose of extracting ore To get at the ore, it is usually necessary to also... following conditions exist: 21 Department of Surface mining English’s lecture for open pit mine speciality 1 The operation will last long enough to amortize the high initial investment 2 The haul is long (in established rail system the average haul is usually more than two miles) 3 Grades can be held to a minimum, usually not to exceed about 4% in favor of a load and about 3 % adverse to a load 4 The rigidly... decreases In choosing a size of a loading unit, the depth and shape of ore body will determine the waste-to-ore ratio, which govern the total amount of material to the moved in given time For any given shovel (or other loading mechanism) size, production rate depends upon cycle time, digging characteristics of various shovel makes, and machine availability Cycle time is a function of pit layout and machine... Its cycle depend upon digging characteristics of the ore, bench height, ete Suppose this cycle time is 30 sec Thus, the machine can produce about 8 to 10 bank yards every minute Now a 35-ton truck size (with a 25-cu yds body) is under consideration Cycle characteristics are as follows: Load time-5 bucket, a bucket: 0.5 minute 2.5 minutes Haul time 2.0 min Position at dump 0.15 min Dump time 0.35 min . and/or concentration. Such tests are essential 10 Department of Surface mining English s lecture for open pit mine speciality for determining in a preliminary fashion likely treatment, flowsheet,. water flow in surface drainage is essential in measuring the availability and suitability of water for process and domestic use. 11 Department of Surface mining English s lecture for open pit. two mining methods is determined as follows: Underground mining cost/ton ore - Open pit mining cost/ton ore Open pit stripping cost/ ton waste Substituting: 12 Department of Surface mining English s