Planeamiento de Mina 2

8/18/2019 Planeamiento de Mina 2

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Planeamiento de minS2 Mining revenues and costs


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ECONOMIC CONCEPTS


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ESTIMATING REVENUES


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ESTIMATING REVENUESThe units in which the prices axe expressed also vary. Some examples in this regard ar

1. For many minerals, the 'ton' is unit of sale. There are three different 'tons' which mare:

If 1 long ton (2240 lbs) of iron ore contained 1% iron (22.40 lbs), then it would containltu) of iron. If the long ton assayed at 65% iron then it would contain 65 ltu. If the quotis 70 ¿//ltu, then the price of 1 long ton of pellets running 65% iron would be:

ESTIMATING REVENUES


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Metric ton units (mtu) and short ton units (stu) are dealt with in the same wreason for using the 'unit' approach is to take into account varying qualities.

2. For most metals, the unit of weight is the pound (lb) or kilogram (kg).

3. Gold, silver, platinum, palladium, and rhodium are sold by the troy ounce. Threlationship between the troy ounce and some other units of weight are given

ESTIMATING REVENUES

Hi t i l i d t


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Historical price dataMineral prices as monitored over a time span of many years exhibit a general u

trend. However, this is not a steady increase with time but rather is characterizfluctuations.

A mining venture may span a few years or several decades. In some cases mine

produced over several centuries. Normally a considerable capital investment is

bring a mine into production. This investment is recovered from the revenues g

the life of the mine. The revenues obviously are strongly dependent upon min

the actual price over the mine life period is less than that projected, serious rewould be experienced. Capital recovery would be jeopardized to say nothing o


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ESTIMATING COSTS


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ESTIMATING COSTSTypes of costs

There are a number of different types of costs which are incurred in a mining o& Weaton, 1968). There are also many ways in which they can be reported. Th

might be:

- Capital cost;

- Operating cost;

- General and administrative cost (G&A).

The capital cost in this case might refer to the investment required for the minThe operating costs would reflect drilling, blasting, etc. costs incurred on a pergeneral and administrative cost might be a yearly charge. The G&A cost could imore of the following

ESTIMATING COSTS


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ESTIMATING COSTSThe capital and G&A costs could be translated into a cost per ton basis just as tThe cost categories might then become:

- Ownership cost;

- Production cost;- General and administrative costs.

The operating cost can be reported by the different unit operations:

- Drilling;

- Blasting;

- Loading;- Hauling;

- Other.

ESTIMATING COSTS


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ESTIMATING COSTS

ESTIMATING COSTS


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ESTIMATING COSTS

ESTIMATING COSTS


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ESTIMATING COSTS

ESTIMATING COSTS Step of Step


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ESTIMATING COSTS-Step of StepStep I

Given the annual production requirements for ore and waste plus the operating scheduproduction rate.

Step 2.Select a basic equipment fleet

Step 3

Calculate the expected production rate for each type of equipment. Calculate the numb

required. Determine the amount of support equipment needed.Step 4

Determine the number of production employees required. Determine the number of su

Step 5

Calculate the owning and operating costs for the equipment.

Step 6

Calculate the other costs.

Step

7 Calculate the overall cost per ton.This procedure will be demonstrated using an example presented by Cherrier (1968). Althouthe process remains the same. The cross-sections through the molybdenum orebody used i

initial mine design has indicated a pit for which- Rock type is granite porphyry,- 32,300,000 tons of waste,- 53,000,000 tons of ore,- Stripping ratio SR equals 0.6:1, and- Average ore grade is 0.28% MoS?.The waste will be hauled by trucks to a dump area. The ore will be hauled by trucks to one oore is crushed and then transported by underground conveyor to the mill.

The step-by-step process will be developed.

ESTIMATING COSTS


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ESTIMATING COSTSStep 1: Dailyproductionratedetermination.It has been decided that the annual production rate will be

- 3,000,000tons oreand

- 2,000,000tons waste.

The mine will operate 2 shifts/day, 5 days/week, 52 weeks per year, with 10 holidays. The ore and waste productio

- Ore:6000tons/shift,

- Waste:4000tons/shift.

Step 2: Selectionofaconsistentsetofpitequipment.The major types of production equipment to be selected are:

- Drills,

- Shovels,

- Trucks.

The bench height has been chosen to be 30 ft. The basic equipment fleet selected consists of:

- 6yd3electric shovels,

- 35toncapacityreardumptrucks,- Rotarydrillscapableofdrilling97/s"diameterhole.

Step 3: Productioncapacity/Numberofmachines.Based upon a detailed examination of each unit operation, the followdetermined:

- Drills: 35 ft of hole per hour,

- Shovels (waste): 630 tons/hour,

- Shovels (ore): 750 tons/hour,

- Trucks (waste): 175 tons/hour,

- Trucks (ore): 280 tons/hour.

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ESTIMATING COSTSFrom this, of the number production units and required scheduling were determined fo

-Ore

1 drill (1 shift/day),1 shovel (2 shifts/day),

3 trucks (2 shifts/day).-Waste

1 drill (1 shift/day),1 shovel (2 shifts/day),4 trucks (2 shifts/day).

The support equipment includes:- 4 dozers (2 shifts/day),

- 2-5 yd3 rubber tired front end loaders (2 shifts/day),- 2 road graders (2 shifts/day),- 1 water truck (2 shifts/day),- 1 explosives truck (1 shift/day).

The reserve production equipment to be purchased is:- 2-35 ton trucks,- 1-5 yd3 front end loader.

In case of shovel breakdown, a front end loader will substitute.

ESTIMATING COSTS


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ESTIMATING COSTSStep 4: Determinethenumberofproductionemployees. A manpower scheduling chart is prepared s2.36. The overall numbers are summarized below.

- 1 assistant superintendent,- 4 shift foreman,- 4 shovel operators,

- 4 oilers,- 14 truck drivers,- 2 drillers,- 2 driller helpers,- 1 blaster,- 1 blaster helper,- 8 dozer operators,- 4 loader operators,

- 4 grader operators,- 2 water truck drivers,- 4 truck spotters,- 4 crusher operators,- 4 conveyor operators,- 10 laborers.

As can be seen, there are 73 production employees. The crusher/conveyor part of the production sdays/week and 3 shifts per day. There is one crusher operator and one conveyor operator per shift.

enough storage capacity so that the mill can run 7 days/week even though the mine runs 5.

ESTIMATING COSTS


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ESTIMATING COSTSStep 5: Determinethenumberofotheremployees.There are four basic departments at the mine:

- Administration,

- Engineering,

- Mine,

- Maintenance.

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ESTIMATING COSTSStep 6: Determinethepayrollcost.Table 2 38 summarizes tie basic annual wage figureclassifications. Fringe benefits amounting to 25% are not included in this table.

Step 7: Determinetheoperatingcostsfortheequipment.The total operating costs for

operations include materials, supplies, power and labor. These are summarized inTab

cost includes the 25% fringe benefits.

Note that there are three different units which have been used to express the costs ($Some conversion factors are required to obtain the desired common values of $/ton. T

- Drilling: 27.2 tons/ft,

- Loading (ore): 750 tons/hr,

- Loading (waste): 630 tons/hr,

- Hauling (ore): 750 tons/hr (3 trucks),

- Hauling (waste): 630 tons/hr (4 trucks).

To simplify the presentation, only two cost categories will be carried further. These areand MEP (material, expenses and power) which includes all of the rest. The ore-wastemade. The results are summarized in Tables 2.40 and 2.41. It is noted that the labor cooperating labor and does not include repair labor nor does it include supervision.

ESTIMATING COSTS


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ESTIMATING COSTSStep 8: Determinethecapitalcostandtheownershipcostfortheequipment. The capitequipment is given in Table 2.42.

During the life of the mine, some of the equipment will have to be replaced. This is indAs can be seen, the original equipment falls into three lifetime groups (5, 10 and 20 ye

summarized below:Life(yrs) Totaloriginalcost($)

5 861,000

10 396,000

20 1,401,000

The equipment ownership cost consists of two parts:(1) Depreciation,

(2) Average annual investment cost.

Straight line depreciation with zero salvage value is assumed. Thus the average equipmper year is $281,850. The average annual investment (AAI) is calculated using the follo

where nis the life (yrs) and CC is the capital cost ($).


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The total AAI = $1,469,930

To obtain the average annual investme(expressed as a ratio) is applied. Includ

and insurance.

AAIC =PxAAI

In this case 10 percent will be used. He

$1,469,930 = $146,993; The average

cost becomes

ESTIMATING COSTS


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ESTIMATING COSTSStep 9:

Calculationofothercapitalexpenditures(mine).The other capital expenmine include those for the required mine buildings and the costs associated wdevelopment period. The following list includes all required mine buildings, ancapital outlays.

ESTIMATING COSTS


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ESTIMATING COSTSThis will be depreciated over the 20 year mine life. The development expenses

ESTIMATING COSTS


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ESTIMATING COSTSStep 10:

Calculationofmillingcosts.In this case the open pit ore tonnage (aver

days) of 8,600 tpd will go to a mill having a capacity of 34,400 tpd. The additio

will be supplied by an underground mine. Since the total mill investment is $48

share for the open pit operation is $12,000,000. This will be depreciated over t

mine life. The ownership cost (depreciation plus average annual investment) pe

The primary crushing will be done at the mine, therefore the first step in millin

secondary crushing. Operating costs for milling are estimated to be the followi

administration and overhead):

ESTIMATING COSTS


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ESTIMATING COSTSStep 11: Expressionoftheminingcosts.There are a variety of ways by which the mining costs can be expwill be presented to illustrate this.

Case1.Directoperatingcosts.The simplest way is to examine the direct operating mining costs for ore a

Step 11: Productivitycalculations.The productivity in terms of tons per manshift can now be calculated.

each employee works 250 shifts per year in producing the 5,000,000 tons of total material. The productidepending on the number of departments included:

ESTIMATING COSTS


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ESTIMATING COSTSStep 12: Mineownershipcosts/ton.As indicated earlier, in addition to the operating costs, there arecosts to be charged against the material moved. These are:

- Equipment ownership costs;

- Development costs;

- Mine buildings.The development and mine buildings will be amortized over the total amount of material moved. In

The equipment ownership cost is

Hence the ownership cost/ton is

Step 13: Totalminingcost.The total mining cost is equal to the total operating cost plus the owners

Note that the ownership cost here is about 27% of the operating cost and 21% of the total mining c

ESTIMATING COSTS


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ESTIMATING COSTSStep 14: Millingcost.As was indicated earlier, the mills operating costs per ton is

Step 15: Profitabilityestimate.The revenues are attributable to the ore and all the costs must now be cha

well.

Current equipment


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Currentequipment


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Planeamiento de Mina 2

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