planeamiento de mina 3

8/18/2019 Planeamiento de Mina 3

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Planeamiento de minS3 Orebody description


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MINE MAPSThe fundamental documents in all stages of mine planning and design are the essential for the purpose of:

- collecting,

- outlining, and- correlating

a large portion of the data required for a surface mining feasibility study. Theseto various scales.The 'scale' is the ratio between the linear distances on the m

where Km is the metric m

1:1000 means that a leng

map represents 1000 me

Similarly a length of 1 cm

distance of

1000 cm. A metric scale

close to the English scale


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MINE MAPSMine planning, for example, should be done at a scale that keeps the whole pit

sheet and yet permits sufficient detail to be shown. For medium to large size m

common planning scales are:

l in = 100ft

l i n = 200 ft

In the metric system, common scales are:

1:1000

1:1250

1:2000

Geologic mapping is commonly done on a larger scale such as 1 in = 40 ft (the

metric scale is 1:500). For planning purposes, the geologic features (outlines) a

onto the smaller scale maps.


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MINE MAPSThe objective of the general area map is to show many pertinent features:

- geology (extent of orebodies, mineralized zones),

- transportation routes (highways, railroad, water routes),

- property ownership and control,

- distances to market, processing or transfer points (applicable freight rates),

- available access,- location of transmission lines for power supply (capacity and construction distances

required for connections),

- location of both present and future potential water supply/reservoir areas,

- areas suitable for tailings, slurry and refuse disposal in relation to mining and processing.

The general mine map is a map of 'medium' scale. It covers a particular region within the general area map. Because the scaleexamined. Figure 3.9 is one example of a general mine map. The types of things which might be shown on such a map include

- processing plant location,

- mine structures,

- power lines,

- water supply,- access roads,

- railroad lines,

- conveyor lines,

- pipelines,

- location of the orebody,

- location of a few drillholes,

- dump/tailing pond locations,

- property ownership and control,

- proposed timing of mining development.


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MINE MAPSThe selection of the map 'north' direction is not universal. Some mines select gtheir north. Others use magnetic north. One large mine reputedly selected minrespect to the direction that the mine manager looked out over the mine fromFor elongated deposits, such as shown in Figure 3.12, the deposit lends itself torunning N-S.

The exploratory and development diamond drill holes are generally laid out in regular pattern. When orebody evaluation is to be done using sections, it is conot imperative, if the drilling and mine grids are aligned. When block models arepresent the orebodies, this is not as important

Table 3.1 contains some guidelines for the preparation of mine maps. The line borders and coordinate systems should be carefully selected so that they can bdo not interfere with the major purpose of the map— that of presenting the ginformation. Modern CAD (computer-aided design) drafting systems have greapreviously, very tedious and time consuming job. It is very important that revisdifferent maps be maintained. The maps coordinates are labelled as 1600N, 14shown in Figure 3.14. Vertical sections are made based upon these plan maps.

3.14, there are two ways of constructing the N-S running sections.


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MINE MAPS


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MINE MAPS


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MINE MAPS


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MINE MAPS


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MINE MAPS

Figure 3.19. An isometric view

Bingham Pit (Kennecott, 1966)


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GEOLOGIC INFORMATIONMining operations at any given mineral deposit may be divided into four stages(Stage 1), is the act of searching for valuable minerals. With the discovery of suproperty becomes a mineral prospect. The property is then explored to gain soinformation regarding the size, shape, position, characteristics and value of the

exploration stage (Stage 2) is successful, then the decision to proceed into Stagmay be made. Detailed (Waterman & Hazen, 1968) geologic information must made available early in this stage to facilitate planning and design. The followinincluded:

1. Geology of the mineralized zone;

2. Physical size and shape of the deposit;

3. Quantitative data on grade and tons of material within pertinent cut-off limi4. Mineralogical and metallurgical characteristics of the ore;

5. Physical characteristics of the ore and waste; and

6. Data on ground conditions, groundwater and other factors that affect mine doperation.

Stage 4 is the actual mining of the deposit.

GEOLOGIC INFORMATION


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GEOLOGIC INFORMATIONHere the focus will be on diamond drilling which produces a core for logging antwo basic types of diamond core drilling are: (a) conventional and (b) wireline. drilling the core is retained by a core spring or core lifter in the core barrel whibehind the bit. When the core barrel is full or after drilling a certain length, the

must be removed in order to extract the core.


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CO OS G O G C O C C


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COMPOSITING AND TONNAGE FACTOR CALCUCompositing

C iti


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Compositingthe diamond core has been extracted it is logged by the geologist and represensent out for assaying. Upon receipt, the assays are added to the other collectedThese individual assay values may represent core lengths of a few inches up to Compositing is a technique by which these assay data are combined to form w

composite grades representative of intervals longer than their own.

This value would then be filled into the box on the table. In this case g is calledcomposite.Although compositing is usually a length-weighted average, if the dvariable, the weighting factor used is the length times the density (or the speci

C iti


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Compositingelevations are selected. This bench compositing is the method most often used for reopen pit mining today. a bench is shown by the horizontal dashed lines. In this particuportion of the bench lies in 'waste.' The bench composite grade is

Compositing with fixed intervals and elevations makes it very easy to present and anadeposit containing a number of drill holes. Some of the reasons for and the benefits oinclude:

1. Irregular length assay samples must be composited to provide representative data

2. Compositing incorporates dilution such as that from mining constant height benchemine.

3. Compositing reduces erratic variation due to very high or very low assay values.

4. By compositing, the number of data, and hence the required computational times,



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GEOLOGIC INFORMATIONTo illustrate the principles presented, consider th

hole log (Davey, 1979) given in Table 3.8. It has

ft high benches and a 5200 ft reference elevation

means that bench crest elevations would be at 52

ft, etc. The upper 38 ft of hole C-22 would lie in

ft would be in bench 2 and the hole

would terminate in bench 3. Using the procedure

composite grade at this hole location for bench 2



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GEOLOGIC INFORMATIONThe mid-elevation of the bench 2 is 5140.0 ft. Composites of the remaining portions of the dribelow this bench may be found in the same way. The results are given below.

If material running 0.3% and higher is understood to be ore, then the ore-zone at this hole extto a depth of 65 ft. The ore-zone composite would be:

In this case when the lengths

are all equal, the average gradeis just the simple average of

the grades.


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METHOD OF VERTICAL SECTIONSINFORM


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METHOD OF VERTICAL SECTIONSINFORMThe traditional method for estimating ore reserves has been through the use omethod has a number of advantages, the primary one is that it can be done byadvantages are that it can be easily depicted, understood and checked. It will bthe method is done by hand. However, a number of computer techniques are designer input/flexibility while doing the calculations by machine. Some compubeen designed to essentially reproduce the interpretation logic currently donegeologists by hand.

Construction ofacross-section:

AnE-Wsection(640N)takenthroughanirondepositisshowninFigure3.22.Tbeginwiththedrillholedataandproceedthroughtothedeterminationoftheadifferentmaterialswhichwouldbeincludedinthefinalpit.Thesymbolswhichh

denotethelayersare:SU = surface (overburden) material (soil, glacial till, etc.) which can be removand blasting.

DT = decomposed taconite.

OP = ore and paint rock.

OT = ore and taconite.

SWT = sandy wash ore and taconite.



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Calculation of tonnage and average grade


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CalculationoftonnageandaveragegradeThis simplified example has also been taken from iron mining practice. The follwill be illustrated:

1. Side completion for sections.

2. Development of a final pit outline including pit ends.3. Determination of tons and average grade for a section.

4. Determination of tons and average grade for the pit.

Although most of the discussion will revolve around section 1 + 00, the same aused on all sections.

Side completion

As described in the previous example, the section 1+00 (Fig. 3.30) has been exthe positions of the outermost drill holes. On the left side of the section, the oout within this zone. The pit slope of 27° has been drawn to pass through the mextension. The width associated with hole 6 would be 50 ft plus half the distan6 and 1. On the right-hand side, the ore is quite thick (25 ft) and would appearslope has been drawn at a point measured 50 ft along the pit bottom. The ore with hole 5 becomes 75 ft.

Calculation of tonnage and average grade


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Calculationoftonnageandaveragegrade


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