INTRODUCTION

In the planet it exists different mineral beds, can find the |minerali| in form |zación| of streaks,

mantles and bodies. The mining undertakings according to the type of bed and some criterions

select the method of exploitation. For the volume of production, it can be of the great mining,

medium mining, small mining and |artesanal| mining.

Ciclo: 2013 - II

Cajamarca - Perú

Facultad:

IngenieríaCarrera:

Ingeniería de Minas.

Docente:

PEDRO REYE JESUS.

TEMA:TRABAJO EN INGLES

ALUMNOS: GUERRERO VARGAS JORGE

2013Fecha: 04-12-2013

Clase: 605751

UNIVERSIDAD PRIVADA DEL NORTE

THE ELECTION OF THE METHOD OF EXTRACTION DEPENDS OF MANY FACTORS, AMONG THEM:

1) Form of the bed: tabulating, cylindrical, spherical.

2) The orientation of the vein: |sub| , horizontal, |sub|, vertical.

3) The continuity of the vein.

4) Size of the mineralized body.

5) Pray-harrow: of high degree, of below degree.

6) The distribution of the minerals of mineral they happen in the bed: |masiva| or disseminating (with a law of cut).

7) Depth of the mineralized body.

8) Depth of the cloth cap.

9) Force of the bed and overload/|host|-rocks rocks.

10) Áof the country available female offender for the mines to open disposition to remainders sky covers a major surface and generates a major volume of remainders.

11) The impacts in the surface: |environnemental|, superficial drainage and the aquiferous of the subsoil, the changes of use, social.

12) rehabilitation preoccupations.

13) Projection of the rates of production.

14) The costs of capital, rate of (financial recovery), the flux of box.

15) The preoccupations of security: methods of mining of surface have a better history of security.

Election of the method of mining:

The election of the method of extraction depends of many factors, among them:

1) Form of the bed: tabulating, cylindrical, spherical.

2) The orientation of the vein: |sub| , horizontal, |sub|, vertical.

3) The continuity of the vein.

4) Size of the mineralized body.

5) Pray-harrow: of high degree, of below degree.

6) The distribution of the minerals of mineral they happen in the bed: |masiva| or disseminating (with a law of cut).

7) Depth of the mineralized body.

According to these criterions that keep in mind to him can select to him the method of exploitation either superficial or subterranean that at the same time these methods of exploitation that at the same time it is subdivided in different techniques to carry out the cycle of mined.

METHODS OF SUPERFICIAL EXPLOITATION

Slice openIn |masivos| beds or of inclined cloaks, the exploitation is taken to end three-dimensional for descending clearing and leveling of ground, with section in form vertical circle |troncocónica|. These methods are the traditional of the metallic mining.

DESIGN OF THE TAJO   OPERATIVO

By keeping in mind the location of the walls with smaller report of rubbish, the accessibility to related facilities as sieves, |chancadoras| , dumps, hoppers of transference, piles of temporal storage, and slope angles meanwhile-|comendados| re ramp, proceeds to establish to him the ramps of access for the slice end, the ramps of access must have a minimum width of 3 times the more big size of the more big truck it is about to work in the mine and the berm of containment must be the ¾ depart of the size of the more big tire and the gradient of the accesses must not surpass 12%.The widthes of highway depend of the size of equipment of transportation to be accustomed, in general in mines to slice open of great scale of closing tightly of bench of 15 meters, 50pies of height, have the highways with a gradient between 8 and 10 %, the total width of highway between 32 and 35 meters.In the market it exists many software that permit make the work of design in a simple way and your flexibility permits make many alternatives, the guide for the design is the proportionate contours for the |optimizadores| , depending of the complexity of the bed the designs can begin from the soul, mediates, lower or a combination of them/it, the others parameters as angles inter, ramp, etcetera, must be the used mimers in the |optimización| , a rule practices of the checkup of the design is that the

difference of tonnage between the reserves or quantity of mineral in the design without ramps and the final operative design must not surpass 2%, this of some way it guarantee that have added additional ramps, rests or used angles inter, different ramp.

Summaries of the method

consist in the economic study of the blocks mineralized and sterile that fall in an invert cone, which it moves systematically through a matrix of block, with the vertex of the cone by occupying, successively, the centers of the blocks. The basic premise of work is that the obtained pure benefits for exploiting the mineralization that it finds in the cone must surpass the expenses to extract the sterile existent thing in this cone. The cones, individually, may not be economic, but, when two or more cones superpose, exists an important part of sterile that is shared for the diverse cones, which generates a change in your economic |estatus|. It splits of a matrix of blocks in which the laws of the blocks, as it beens commented previously, have calculated for the opportune methods ( for example the |krigeaje| or inverse of the distance ). following establishes to him a minimum law of exploitation and, die a certain angle for the slope of the short ( for example 45 degrees ), places to him the cone in the first block, by beginning for recover and for the left. The economic viability of the cone it calculates by using the formula:

It splits of a matrix of blocks in which the laws of the blocks, as it beens commented previously, have calculated for the opportune methods ( for example the |krigeaje| or inverse of the distance ). following establishes to him a minimum law of exploitation and, die a certain angle for the slope of the short ( for example 45 degrees ), places to him the cone in the first block, by beginning for recover and for the left. The economic viability of the cone it calculates by using the formula:

Sequences of extraction of cones: This takes root in the sequence with which you are analyzed the blocks of the model.

In the figure it can appreciate the benefit that reports the extraction of each block. The blocks with benefit positive already they are had discounted which hill extract this block or cost mines (-10). If the first cone it builds in the block (1) and by supposing an angle of slope to, then this block cannot be extracted ( benefit = -10 ). to the is not feasible the extraction of the block (1), the second cone it builds in the block (2), where the pure benefit of the cone is of +10, being accordingly advantageous your extraction, by remaining the figure of the following form:

If the benefit is positive, all included blocks in the cone mark and it is removed of the matrix of blocks, are which it is creates a new surface. On the contrary, if the benefit is negative, the matrix remains to him how are you and the vertex of the cone it moves a second block whose value is for on the minimum law of exploitation, repeating, then the process.

Continuing with the sequence, the third cone it builds in the block (3), by resulting a benefit of +30.

Of this analysis it is concluded that the three blocks with economic value major that zero are extracted with an economic benefit of +40, however a correct analysis must obtain a |pit| with value of +60, stopping in your place the block (3) with your respective overload, as can see in the following figure:

Of the previous it is let loose that the incorrect sequence with which it is analyzed the cones, produces economic losses whose magnitude, obvious, depends of the complexity of the mineralization, of the variability of the laws, etcetera. The problem before describes is resolved for the new algorism by introducing the “cono negativo” concept, algorism it consists in extracting all blocks with positive benefit, afterwards to return them to the boast with your respective overload and so analyze the convenience of extracting the or eliminate the. In the presentee example previously, it is appreciated that when returning the block (3) with your respective overload, produces to him an economic benefit

because frees to him a value of +20, this indicates that this block to the does not extract in your more favorable condition it must be eliminated of the analysis. In practice the technique of the negative cone presents similar deficiencies to the obtained by means of which could be called the positive cone, however a simultaneous analysis of both techniques (positive and negative cone) produces satisfactory results. This simultaneousness is she who it become fulfilled in the stage 1 of the Lemieux algorism.

Cones with overload related: This is the main contribution of the method of the mobile cone |optimizante|, consist in analyzing cones that have overload shared, for example:

The blocks (1) and (2) have a benefit of +70 ( included the cost mines ). to analyze cones individually, appreciates to him that is not convenient the extraction of this blocks, because each case the pure benefit of the cone is -10.

Notwithstanding if analyzes to him in its entirety sees that is advantageous your extraction, because this has with oneself a benefit of +40.

Input

a. Metallurgical recovery of the plant.

b. Selling price of the mineral.

c. Costs of mineral extraction( cost mines, cost plants, services, etcetera.)

d. Costs of sterile extraction and transports to dumps.

e. Á|ngulo| of final wall( model |geotécnico| ).

f. Density of the sterile thing.

g. Density of the mineral.

h. Model of blocks( space distribution of laws for blocks ).

Output

a. Pit final ( economic limit of the Pit ).

b. Number of profitable blocks.

c. Quantity of mineral and |esteril| to extract.

d. Partial and total costs of exploitation.

e. Partial and total benefits.

Practical example of the methodIn the following outline a profile of a model is presented of subdued blocks to the algorism of the mobile cone |optimizante|, where each block is defined for an economic value, that is to say which is important economically your extraction. It is so the blocks with negative value represent to the blocks of sterile with your cost of associate extraction (, 10 ) and the blocks of mineral are represented for the global benefit that reports your extraction ( benefit global = revenues, costs = 810-10 = 800 ).

In the previous example we can observe that the extract the block of positive value (+800) and your 15 blocks of sterile associate ( -10 everyone ), generates a final benefit of +650, corresponding to the benefit to extract this block with your on load associated.

OPEN PEATS

These methods apply in ceilings beds or horizontal, with a few coverings of sterile inferiors, in general, to the 50 m. consist in the |unidireccional| advance of a module with a single bench from the one which is carried out the beginning of the sterile and poured of this one to the hollow of the previous phases. The mineral is then extracted from the buttom of the exploitation, that coincides with the wall of the deposit.

After carrying out the excavation of the first module or hollow initial, the sterile thing of the following is poured in the own hollow of the previous phases, in this way that it is, for nature, the more representative methods |delos| of transference.

The machinery that is used depends of the volume of reserve |extraíbles|, being in the big mines of frequenting application the |dragalinas| and, in the small, if not justify the strong inversions in machinery, the conventional equipments as the caterpillar tractors, the excavating hydraulicses, the Pallas loaders, etcetera.

TERRACESThis method is based in a mining of clearing and leveling of ground with advancing |unidireccional|. It is applied in relatively horizontal beds, of one or several mineralized levels and with potent coverings, but that permit place the sterile thing in the created hollow, by transporting it about the exploitation.

The depthes that are reached are important, existing almost exclusively a limitation of economic type in the determination of who is the last mineralized level that will be exploded. just as it happens with the methods of open pie and just as it beens indicated, a |rrelleno| edict is carried out of the created hollow, for which, from the viewpoint of the restoration of the terrains, the possibilities of action are big.

The equipments and mining systems that it is used are very varied, from the totally discontinuous thing with conventional equipments of load and transports, until the continuums, with transport with girt and crushing in the own exploitations, that possess a high degree of electrification.

CONTOURIn beds of charcoal with cloaks fallen, of reduced power and generally unfavorable topography, apply the methods known below the denomination of mining of contour.

They consist in the excavation of the sterile and of the mineral in transversal sense to the outcropping, until reaching the economic limit, by leaving a slope of unique bench and longitudinal progression by following the mentioned outcropping.

Die the great development of these exploitations and the scarce depth of the hollows, is possible to carry out a transference of the sterile for the later recovery of the terrains.The machinery that is used is generally of the conventional, driven type for Diesel engines

The filling of the hollows is accustomed to carry out once it beens reached a situation that permits the poured in the exploitation.

QUARRIESQuarries are the generic term that it uses to refer to the exploitations of industrial, ornamental rocks and of materials of construction.

Constitute, with a lot of, the more important sector as for number, since from very ancient been come to him by exploiting for the extraction and supplying of raw materials with am accustomed end in the construction and in works of substructure.

In other times, due to the relatively small value that had the extracted materials, the quarries put very near to the centers of consumption and possessed some generally reduced dimensions.

Nowadays the situation is very different, as will be seen farther on.On line general, the method of applied exploitation is generally those of clearing and levelings of ground, with one or several levels, by putting a great number of quarries to intercedes side.The quarries can be subdivided in two groups:

• The first, in which wants to obtain to him an all-one fragmented adapt to feed to the plants of treatment and obtain an appointed to product to the in form construction of arids, to the manufacture of cements, to the manufacture of industrial products, etcetera. In this type of exploitation they give quarries where the extraction is not careful and give to him big altitudes of bench.

• The second, dedicated to the careful exploitation of big |paralepipédicos| blocks, that afterwards it is stopped and elaborate. These exploitations are characterized for the great number of benches that they opens to start the blocks and the special machinery with she who it is obtained drawing of clean cut.

GRAVERASThe detrital materials, in any way whatever the sands and the gravels, taken shelter in the deposits of valley and terraces of the rivers, they are to object of an intense exploitation due to the claim of this materials for the sector of the construction.The sands and the rolling stones are found little |cohesionados| , for which the fancyworks of beginning it is carried out directly for mechanical equipments. The exploitations are accustomed to take to end in a single bench, with a lower depth, in general, to the 20 m.When the formations are found in high levels, use conventional equipments, in any way whatever the Pallas loaders of wheels and the tipcarts. However, it is frequent that the materials they appears in contact with the |subalveo| or the aquiferous |infrayacentes|, by employing then other mining equipments in any way whatever the dredgers, the |dragalinas| or the lectures, by making room for the later formation of lacunas.

HYDRAULIC MINING. DREDGING

In special mineralizations, in any way whatever the golden metallurgies, cassiterite, etcetera, etcetera., contained in floods, results interesting the application of the method of the dredging, inundating previously the area of exploitation. This method is economic when the own water of flood it uses in the process of concentration, as occur with the gravimetric separation. The dredgers, besides the system of extraction that use ( potholes, middlingses of cut,etc.),they can reach to it incorporates the own plant of treatment on the platform ( screen, cyclones, |jigs|,etc.),with capacitance to treat big volumes of material, and a system of evacuation of sterile to the area already exploded.Notwithstanding, nowadays it is more frequent to observe that dredges and plant are floating but are separate among themselves and connected for a pipes by means of the who the dredger reconnoiters the extracted material to the plant.

CUT AND FULL( CUT AND FILL )

It is an ascendant method (embossment). The mineral is broke for break up horizontals and/or vertical by beginning for the body of a slice and advancing vertically. When it has extracted the complete fringe, the corresponding volume with sterile material is filled ( filling ), that it servs as floor of work to the workers and At the same time permits maintain the walls, and in some special cases the roof

Characteristic of the method

The exploitation of cut and it fill can be used in beds that present the following characteristics: Strongly dip, superior to the 50º of inclination. Characteristic |fisico|-|mecanicas| of the mineral and rock of relatively bad box

(incompetent rock). Moderate power. Regular limits of the bed

Advantages• The recovery is near to 100%.• Is highly selective, which is important that they can work to him sections of high law and

leave those areas of low grade without exploiting.• It is a sure method.• It can reach a high degree of mechanization.• It fits to beds with physical properties – mechanical incompetent.

Disadvantages:

• Cost of high exploitation.

• Below performance for the paralyzation of the production as consequence of the filling.

• High consumption of materials of fortification.

Room and Pillar

The method of Room exploitation |and| pillage or also chambers and pillars, consists as your name indicates it, in the exploitation of separate large broken-down houses for pillars of support of the roof. The recovery of the pillars can be or partial or total, in this the last one marry, the recovery is accompanied of the controled sinking of the roof that can be carried out together with the exploitation or at the end of the life of the bed, logically the sinking of the roof in this case is totally controled.This method of exploitation is applied amply and in the last years it beens developed enough, due to your below cost of exploitation and while permits up to a point a moderately selective exploitation. The beds that better it is presented for an exploitation for Room |and| pillage, it are thoses that present an angle of tossing in a blanket below, although also is applicable in beds of tossing in a blanket between 30° and 40°,that is to say, in beds of critical tossing in a blanket, where the mineral it cannot drain for gravity

• The method up to a point is selective, that is to say more poor areas may not be exploited without affecting chiefly the |aplicabilidad| of the method.

• In important beds it can be moved close to a well complete mechanization which reduces amply the costs of exploitation.

• In beds that they crop out to the surface it can be made the whole development and preparation for mineral, or in other case the developments for sterile can be very insignificant.

• permit the exploitation without problems, of bodies mineralized located parallel and separated for areas of sterile.

• The recovery of the bed still is not of 100% can be moved close to satisfactory recoveries in the neighborhood of the 80 to 90 %.

ADVANTAGES

• The method up to a point is selective, that is to say more poor areas may not be exploited without affecting chiefly the |aplicabilidad| of the method.

• In important beds it can be moved close to a well complete mechanization which reduces amply the costs of exploitation.

• In beds that they crop out to the surface it can be made the whole development and preparation for mineral, or in other case the developments for sterile can be very insignificant.

• permit the exploitation without problems, of bodies mineralized located parallel and separated for areas of sterile.

• The recovery of the bed still is not of 100% can be moved close to satisfactory recoveries in the neighborhood of the 80 to 90 %.

DISADVANTAGES• If the bed presents a very irregular mineralization, so much in run as in power could

reach to affect the exploitation, limiting a lot of the planning of the method, as likewise the perforation and cause problems of load above all for possible mechanizations.

• Problem of tossing in a blanket of the bed, when the tossing in a blanket this very near the critical tossing in a blanket (45°), produce problems for the movement of the mineral in the large broken-down houses and still this problem is more serious, if trade of narrow mantles. In the case of potent mantles there is problems in the mechanization of the perforation which is translated in difficulties of mobility when using the heavy equipment of perforation.

• Dilution of the law: it is a problem that is very important and that in the case of weak roofs can be to cause that it reaches to limit the application of the method.

MÉTODO DE CÁMARAS POR SUBLEVELS ( Sublevel |stoping| )The method of beginning from sublevels normally emploies to him in very regular beds, in those who the mineral and the rock of the cloy are resistant you. The method is characterized for your great productivity due to that the fancyworks of preparation are carried out in your major departs in the mineral. It is applied to nurseries of high slope, in those who the mineral falls for gravity in the open hollow and that permits the perforation of long manias of clearing and leveling of ground or in fan. These methods need a great preparation and it requires in general that the nursery is potent. The best distance between sublevels depends of two parameters: the cost and the dilution, and between those who it is searched for a solution of commitment. The costs, in general, decrease when increasing the height (current tendency), but increases with it the dilution and some particular cost, above all when recovering the masses of protection and pillars. The longitudinal chambers, when discovering a major surface of cloy you, it are worse for the dilution that the collateral relatives. But it theses last need a few pillars that represent normally the 50 by the hundreds of the mineral of the nursery, while in the longitudinal thing is a lot of minor. At present the distance between levels oscillates between 100 and 130 m for the whole chamber and the sublevels put to him each 30 m of height.

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GEOMETRY OF THE METHOD. The disposition of the chambers with report to the bed can be of two types: longitudinal or transversal with respect to the direction of the same thing. The first is applied in prolific whose power does not exceed the possible width of the chamber, that is, about 20 m according to the

quality of the terrain. When the power exceeds the convenient dimensions for the stability of the chamber it becomes tainted at the disposal of transversal chambers.

BEGINNING OF CLEARING AND LEVELING OF GROUND WITH PARALLEL MANIAS. In vertical beds this system has the advantage of can give a spaced out provide with uniforms to the manias with some ideal conditions of distribution of energy and of breakage. CAMARAS POR SUBNIVELES( I level vertical circle )- Widening of the sublevel until the width of the chamber

- Parallel manias of until 165 mm. Perforation with hammer abreast- Loads spaced out and |secuenciadas| to reduce vibrations

EXPLOITATION FOR SUBLEVELS WITH MANIAS IN PARALLELThe chamber in its entirety it prepares as beens exposed to him previously. One time open the frontal clearing, to start the beginning, and beginning by the sublevel more below, prepares to him a cornice in each sublevel and to all the carried forward width of beginning,

DE LABOREO DE MINAS foundations as it sees in the previous figure. From these cornices perforates to him with parallel descending manias, that after fly to him. The blowing up begins by to him down and in order ascendant sublevel is made to sublevel. The distance between sublevels varied between 6 m and 20 m and the personnel has to work with safety belts. At present this method has been substituted with advantage for those of " level with big manias " and for it it gets a job less and less and only in very special cases.

B) BEGINNING WITH MANIAS IN FAN. CAMARAS POR SUBNIVELES ( manias in fan )

- Manias of 51-102 mm. of diameter perforated with hammer in middlings- Pneumatic load mechanized of the explosiveIn this system they can perforate the manias, according to the outline of fan, with the security it gives perforate it in the gallery of the level. So it can be taken the so moved forward perforation as want to him, limited only for the risk to lose manias for the downfalls of rock when advancing the labor. The distance between sublevels depends, between other factors, of the possibility to control the direction of the manias to secure a " spaced out " and correct "stone" in the extreme buttoms of the same. This technology progresses constantly. Normally begins to him the blowing up for the more low sublevels, but by preparing the perforation and load of all manias before starting the blowing up. are accustomed to perforate until six fans in each sublevel, flying only the three first now; sometime they blow up to him one by one, to examine your effect. The design of the fan is of great importance to get good fragmentation and a maximum of recovery. The parameters that it is necessary to keep in mind are:

- Longitude of best perforation: of 20 ms to 24 pasts m those which does to him more difficult the control of the deviation of the manias.

- Fragmentation: it can be achieved by reducing the "stone" or the "”espaciado" of the manias.

The first varied between 1.6 m. and 3.3 m and the same thing the " spaced out " of the buttoms of the manias. A good fragmentation avoids the play billiards. are accustomed to blow up several fans,

DE LABOREO DE MINAS foundations that it is separated of 3 to 5 m according to the quality of the mineral and the diameter of the manias, by employing delays |micro|. EXPLOITATION

EXPLOITATION FOR SUBLEVELS WITH MANIAS IN DESDE 2 GALERIAS FAN- The distance between levels and the width of the chamber bears upon the disposition of the

fan and in the number of manias. Although also the influence can be inverse, because the

magnitude of the manias can decide the distance between level and the number of the same.

- Also the long manias of each fan can be intercrossed with those of the following, to improve the fragmentation.

EXPLOITATION FOR SUBLEVELS WITH MANIAS IN DESDE 2 GALERIAS FAN- The distance between levels and the width of the chamber bears upon the disposition of the

fan and in the number of manias. Although also the influence can be inverse, because the magnitude of the manias can decide the distance between level and the number of the same.

- Also the long manias of each fan can be intercrossed with those of the following, to improve the fragmentation.

FOUNDATIONS OF TILLING OF MINES

- The presence of stratums, it assemble and judge, can help or hinder and must be had in account.

- It is indispensable the employment of detonators of delay in the blowing up, by beginning in the fan for the vertical mania; in tight chamber consummate to him more explosive for ton for the same fragmentation.

- Finished the beginning of the mass of the chamber, they perforate to him the masses and pillars of mezzanines and between chambers with deep manias and they flies away to recover them.

Advantages and inconvenient. The advantages of this method, above all in your variant first, are: - The work is endless, without interruption to fill. - The cost for ton is below and demands little manual labor. - The report of the production to the preparation is high. - There is great security for the personnel ( has not to enter the chamber ). - The ventilation is good. - The conservation is minimum. - The whole machinery recovers to him-when finishing each chamber. The more signal inconvinients are: - It is not possible the selective exploitation. The law interceded privy it is necessary to keep it

by combining the beginning of several chambers. - It is necessary a maintenance service of rigorous equipments and for it expensively. The

maintenance service is more expensive than those of production. MANIAS CHAMBERS MANY PARALLELS OF CLEARING AND LEVELING OF GROUNDIn this variant suppress the sublevels, and the chambers prepare to departs from the two galleries head first and bases of exploitation, between those who is perforated a chimney of communication in the frontal foreseen wall in the chamber. In these galleries head first and it bases practices to him an embossment of a few 4 m and they widens until the dimension that it is has foreseen for the chamber. following start the blowing ups about the chimney, emploied as squeezes through, to leave pharmaceutical preparation the front of beginning of the chamber. Remains so particularized the block of mineral of the chamber, limited for two touch lightly in passing or open spaces, in middlings and bases, of 4 ms of high and, the length and it wide that it is |dimensione| for the chamber, and for the front with a vertical clearing with a thickness of 2 ms to 3 m, the court width and the height of the level. So it remains the in form front of bench, whose height depends of the dimensions of the chamber and of the possibilities of

FOUNDATIONS OF TILLING OF MINES

Perforation of the manias. In the states current of the technology consider the 60 m as the maximum height |optima|. One time pharmaceutical preparation the bench, perforate the manias with diameters of 115 mm to 200 mm, and longitude between 50 m and 90 ms, although the best maximum is of 60 ms. The blowing up begins about the initial chimney, emploied as squeezes through; after it follows until completing the clearing that servs as exit to the throws of clearing and leveling of ground.

With regard to the process of fragmentation, the study of the blowing up must persecute two objectives: reducing the cost of production and it minimizes the damages produced for the blowing up. The process of load, split and transports can be followed of two trained. In an uses to him a big machine L.H.D., that loads, transports the mineral to the station of split and flows in it. Other variant consists in loads with small shovel and unload in a transporter in the same chamber. This takes the brute mineral to the breaker.

A variant of this |cuano| method is not convenient nor possible delimit blocksfield glasses of mineral consist in applying the long throws in fans, as sees in the following figure, being as for the rest the similar design to those of the long parallel throws. As has this, the main advantage of these methods is the suppression of the sublevels. CÁMARAS CON BARRENOS LARGOS EN CRÁTER ( vertical Crater Retreat, VCR ).This variant is known as court method V.C.R., that can be translated for"Chambers with crater blowing ups in retired ascendant ". not variant of this method if not is convenient nors possible to delimit blocks.

CÁMARAS ALMACÉN( Shrinkage |stopes| )This method is fited for vertical seams, with not a lot of boosts and with sufficient regularity and

stability of cloy you to permit the Fall for gravity of the mineral. The nursery must have some

geometric similar characteristics to the privies for the methods of sublevels. It deals with of a

method of transition.

It uses as support the own broke mineral, that it neglects oneself in the chamber and to this

must your name. When the surface of the rock remains exposed to the effect of the elements

on soil, disintegrates to him and slackens and with the mining works induce tensions in it. If the

rock opening the chamber is of consistency intercedes will let loose even or blocks, but if it are

beginning to fill to him the chamber with the broke mineral is braked the take-off of the rock and

fall. However, the warehouse chambers must be emploied in the case of cloying you with friable

rocks because can press on the broke mineral and make difficult your exit in the load. when

break to crush the virgin mineral with the blowing up, the excerpts occupy major volume that in

situ. This expansion it knows one another as index of sponginess and is accustomed to vary of

1.3 to 1.5, ( which wants say that the volume it increases between 30% and 50% ), according to

the degree of fragmentation.

According to the power of the nursery or court width four forms of geometry of the base is can

adopt of the chamber; In the first to ) suppress the masses of the gallery of base and the

mineral is loaded on a spread out of wood, reinforced for propping ( for it the power has to be

small ). In the second b ) and with boost elders suppresses the propping and open to him

funnels in the mass of gallery.

In the case of producing big blocks that must be stuffed to him employ some |sobreguías| of

playing billiards between the guide and the exploitation. The practical convenient interval

between loading platforms is of 8 ms to 10 m, it who permits a load in good conditions and also

a floor of plain work on the mineral amount of wine laid in vats for aging. To start the

preparation of the exploitation it begins for perforating a chimney in the center of the

future chamber and other in the center of the lateral masses of separation between

chambers and these chimneys serve also for the ventilation. Again, it mounts in the

chamber, between the mineral in the part of the wall, strainers put into tubes each 45 or

60 m, for step of personnel and air intake and is to can also use auxiliary ventilators to

force the ventilation of the air in the chamber. Again prepare only the extreme

chimneys.

With cloying you and appropriate roofs have reached to to him court widthes of 25 m but in these cases it must be considered the convenience to use the methods for long throws. sometimes in wide seams the chambers are opened in transversal direction to the seam. Each chamber it separates of the adjacent thing for a pillar of virgin mineral, to reduce the light or vain excessive of the same thing

The mineral is started along the chamber for slices in successive embossments of 2 to 3.5 m of

height and with the width of the chamber, with horizontal manias or vertical circle of 3 to 4 in

length m; with these the last ones, can be perforated more meters and give some blowing ups

of tonnage major, by using delays for the ignition of the same thing;

moreover, they are independent the cycles of perforation and blowing up. The broke mineral

servs as floor of work.

The cycle of exploitation consists in perforating, blow up, load and bolt, accompanied for a

partial periodic extraction of broke mineral, since after each blowing up the full mineral the

whole hollow of the chamber and it is necessary to extract the 40 by the hundreds of the same

thing for the lower loading platforms until recovering a new empty space it gives birth of 2 ms

between the broke mineral and the virgin corona, that it perforates again. If the mineral is blown

up with horizontal manias, is precise to load it before each blowing up. The mineral it remains in

the chamber is kept to a level that it permits your use as floor of work for each embossment,

until reaching to him the level of the pillar of corona.

In that moment it begins the operation to empty the whole mineral amount of wine laid in vats

for aging. It must be calculated the quantity of mineral to extract because inasmuch as if flows

to excess will be precise to mount on the floor of scaffolds amount of wine laid in vats for aging

mineral in order that the jackhammers reach the corona. sometimes it can look as if the floor it

is priced at the correct height, as consequence of having a hollow below in the inside of the

broke mineral but if this hollow sinks to him can trap to some miner in your downfall.

In order that they are satisfactory the storages in the chamber, the mineral must go down freely.

A loamy material or too much die can originate hang. They can be stuffed from recover to

eliminate the, but is generally difficult to make it; moreover, the mineral must be compressed

nor cause subterranean fires or deteriorations in your storage in the chamber.

In some cases, the periodic extraction for the loading platforms of base increases the risks of

accident and the dilution of the mineral for deterioration of the cloy you. To avoid it it can stop in

the inside of the mineral amount of wine laid in vats for aging a few strainers put into tubes,

whereby extracts to him the leftover mineral.

In some case they leave occasional pillars in the warehouse chambers when the cloy are false

you and in other cases when the mineralization decreases a lot of or disappears, because is

uneconomical to start the; these occasional pillars provide an additional support. When give up

to him these pillars must be sharpened in your soul, leaving the with two slopes of 50° to 60° in

order that the mineral when falling slips with facility and form to him hang on them/it. Also it can

be emploied bolts for weak areas of the cloy you, in order to avoid that lets loose pieces of

rock and soil the mineral.

Once the beginning has arrived until the pillar of corona of the superior level, flows the mineral

amount of wine laid in vats for aging until emptying the chamber. The sides below the mass of

corona can be bolted to increase your stability and avoid that they sinks before emptying of

mineral the chamber. To avoid the excess of dust in the loading platforms of mineral, before

emptying the chamber, install irrigations of water pulverized. Also it can be blown up the mass

of corona of the chamber before give up the, and sink it to all the length. If moreover proceeds

to fly to him with manias in fan the pillars between chambers the whole can be considered a

sunken block. Can be this one the road to rehearse or start a method of sinking for blocks.

In the blowing ups they can produce blocks of mineral that exceed the convenient size to the

transport. They can give three cases: that the load is of free exit, without strainers, in whose

case it grinds in the corresponding station. But in the others cases it is necessary to stuff the,

departs in the chamber of beginning and above all, in a level of playing billiards moving the

mineral with lectures or leveling harrows (Scraper).

These fancyworks raise the price of the preparation and for it it normal today is the c disposition

) in which drops a hint freely the mineral and your own slope regulates the load with L.H.D.

The advantages of the warehouse chambers are:

• In agree appropriate can be more cheap than the method of cut and it fill.

• The mineral amount of wine laid in vats for aging acts as floor of work, even to scaffold

in the beginning.

• The perforation and blowing up in the warehouse chambers are more effective than in

the method of full slices, because is not a cyclic work as in this one.

• There is not strainers in the chamber nor, therefore, works of conservation of the

same.

• There is not that moving the mineral during the exploitation, although, sometimes, it is

necessary to track it to level the platforms of work of the perforating motives.

The inconvinients are:

• The corona and sides of the chamber must be healthy and firm. The ideal slope is the

vertical circle, but considers to him applicable until 50°.

• In some cases is difficult to leave the wall short, since is to produce irregularities in the

same that can be causes of " hollow colgados” when retaining the mineral; for it there is

need of giving up something of mineral or free part of rock of the gable end, according

to the circumstances.

• The rocks that give away the cloy have a bowel movement you the mineral. The

mineral is subject to oxidation in the chamber, which it can occasion difficulties in the

flotation and also produce fires the content in sulphur is sufficient.

C0RTE AND FULL DESCENDING. (Undercut and fill )

In this method the beginning is carried out in horizontal slices that it is filled placing previously a

slab of poor concrete or it fill cemented that servs as artificial roof for the following slice. This

method substitutes to those of stops and it fill ascendant in the cases of false mineral and

fractured whose corona can decrease and complicate the exploitation.

Cut and it fill descending

It is a method that presents the following advantages:

• permit recovers the mineral in very high proportion

• avoid the instability with mineral and cloy you false.

• It eliminates totally the support of the coronas.

• Nevertheless it increases the security.

One of the first applications of this method carried out it the japaneses for the integral

exploitation of a mineral mass of sulfides of copper of the nursery of Juroko and was presented

for first time in the international congress v of mining.

The mass was of 800 m quickly, 500 deep m and 20 ms of thickness. The law was of 2.5% of

copper, 1.3% of lead, 4.2% of zinc and 18% of pyrites, 1gr golden and 90 |gr| of silver for ton.

The mineral and the cloy were little resistant you. Moreover the presence of water made the

conditions of difficult exploitation.

divided the bed in bloc of 30 x m 20 x m 10 m (to 40 m of height) were pleased for two

openings in the extremes, a for personal and material and the other for exit of mineral. A lower

gallery linked the two openings.

The beginning provided oneself with fancyworks of traverse, in form of galleries of 3 ms of wide

and 2.5 of height, that it advanced from the first gallery of link by mixing with pillars of the same

width. When it finished to him a slice it is prepared in each chamber a floor of 50 cm of

reinforced concrete with wire netting on board of wood. The concrete with 15 % of cement more

skin and clear out without muds, in parts it equal. The 2 remaining meters filled with fill wither

and without cement. following started to him and filled the masses in the same way. Finished a

slice begins the inferior. The performance of this exploitation reached to 20 t/hombre/día, which

in thoses times was all a record.

SINKING FOR BLOCKS. (|caving| pad)

This method consists in starting a block of mineral in a nursery of big dimensions for sinking of

the mineral, that it is beginning to serve for the base of the block.

It begins for dividing the nursery as a whole blocks whose horizontal section is generally

superior to 1000 m2. In the base opens to him a great horizontal clearing, with which you are

removed to the mineral mass your support.

It prepares to him the mass with a net of galleries and intercrossed chimneys in the wall. The

clearing permits to the mineral fracture and sink . The area of fracture goes up progressively in

the whole mass. as it progresses the sinking, the better fragmentation, the mineral break to

crush to him and so can be loaded in the base, in the numerous points of load.

The method needs for your application, besides a few very big and potent nurseries, the

following conditions:

• A mineral that sinks and fragments naturally well, one time dug under in your base.

• An enough resistant wall, since the whole substructure of the exploitation it

perforates in it.

• A surface without problems to turning upside down it with strong craks and chasms.

The more common application of this method is in the big nurseries of minerals of iron or of

very disseminating low-grade ores in desert-like and isolated areas.

For the preparation of the block to sink it begins for perforating a series of galleries of ready

load according to a regular outline; é|stas| are linked with the base of the block, or with the

clearing, with funnels and chimneys. These galleries will suffer pressures forts. All works are

must finish before feeding the sinking.

During the production or sinking not perforates to him, except to break some block of too

much size. To get it recovers well the mineral and avoid the mixture with

Outline of sinking for blocks. Block Caving

sterile is precise to get that the superior surface of the block that is sunk forms an endless

plane. For it it needs a rigorous control of the amount of mineral that it serves in each point of

lower load.

The fragmentation carries out to him naturally and the stickings can cause very serious

problems and mineral losses and soiling of the same thing.

In the study of the quality of the mass it is useful the parameter of quality of rock (R.Q.D.) the

trials in test tubes to decide the resistance to the breakage are not so interesting as the know

the condition of the mineral to fragment in small pieces. For it it must be studied the disposition

of crossroadses, it assemble and plane of stratification.

Must not stop hollow important between the loose mineral oblique line and the mass that is to

fragment, because if this one causes something to lean its vertical position to him produces a

true explosion when compressing the air of the hollow with a sequel of damages and victims.

As the terrain it is fractured for the sinking is easily thats to penetrate he the waters of surface

and those of the aquiferous mantles and inundate the fancyworks. It must be foreseed a

capacitance of convexity for the avenues maxims that can be hoped. When it progresses in

depth the sinking and the remains of the cloy are beginning to fill you the hollow, the rocks act

as a sponge and the |escorrentías| of the water of shower must be channeled in surface.

If exists a great aquiferous will be to form up potent gas stations that raise the water from under

the base of the sinking.

The advantages of the method of sunken blocks are:

• Cost of production very below; it is almost so below as those of the short thing.

• Once the sinking begins, gets to him a high production.

• They can be normalized the conditions by increasing the security and efficacy of work.

• The frequency of accidents is clearly very low.

The inconvinients are:

• The inversion of capital is big and the long preparation.

• The mixture of mineral and sterile, as well as the losses of high mineral.

• There is that it watches rigorously the discharge of the mineral and is not easily.

• The next low-grade ore to the covering and the bastards of the nursery it soils

excessively if the control of the sinking is not to too good.

• It is not possible the selective exploitation of mineral of high and low grade. Only it can

be extracted all together.

• As in the warehouse chamber the mineral oxidizes to him.

to this method would be interesting to apply you the theory of the flux for gravity, studied in

the method of sinking for sublevels, to define all parameters of design although has not carried

out to the date.

SINKING FOR SLICE LENGTH. LONGWALL MINING METHOD.

The method of slicing length is a method of simple preparation and has the advantage to

provide an endless production with the possibility of a very complete mechanization, it who

improves the productivity, the security and the health of the personnel.

The ventilation is good and the personnel works in the front always below the shields of support

for which this method is enclosed more sure than those of chambers and pillars. As moreover

this method include the total sinking of the mined, the recovery of charcoal is major and the

relatively uniform |subsidencia| and completes.

The depth of work is put between the 60 and the 850 m. It is applied to cloaks of charcoal

between 1 and 4 m of power. to bigger powers it divides the cloak in more tight sections, but

has arrived in Poland to employ grubbers or machines of cut of until 8 m of capacitance of cut.

In England, where it sprouted the method and gave a great prestige and advantages to the

National Coal Board for your export to other countries as USA, Chinese or Africa of the south,

has reached to to him a design completely |robotizado| of the exploitation of lacunas it gelds of

charcoal and is applicable to other soft minerals as the potashes, plasters and other.

The entrances to the quarters or panel are those of middlings and tail. The entrance head first it

is the custom for the entrance of ventilation, the transport of the charcoal, the entrance of the

personnel and of the supplies, while that the entrance of tail it gets a job for the return of the air,

The beginning is carried out with a grubber of she who exist several models or types and that

flows the broke charcoal on a metallic |panzer| that transports it outside of the slice, to transfer it

to a system of tapes that extract it outside of the mine or until the well of vertical extraction.

Uses to him a commercial hydraulic propping (autodesplazable) to maintain the carried forward

roof and it moves forward after each passing of the endless grubber. The entrances to the panel

or quarters keep by means of bolted; in the entrance of tail put moreover an or two case out of

keys or small castles and in the gallery of entrance also along 30 to 150 m.

The width of the panel is between 100 and 300 m and the longitude between 500 and 4000 m.

If the width of the panel is lower to 100 m it prefers employ to him in the beginning with mine-

laying endless and then the method his name is of slice stop.

It stands to reason that the width of the panel is very important, because a slice more wide

length will increase the production of charcoal. The factors they influence the width of the slice

View of a slice length in 3 dimensions

are economic ands technical. From the economic viewpoint the increment of the width will

reduce the number of panels in the mine with which will decrease the cost of the preparation,

will increase the recovery of charcoal to credit side less good mud-runner pillars, and it is

increased the production of charcoal until a certain is bounded ( widthes of bigger panel of 300

meters have a smaller influence in the production of charcoal )

From the technical viewpoint it is possible to reach to widthes of 300 meters with strong

productions; however it must be had in account that the width is limited for the electric power

required for the armored transporter and the structural efforts that it has to support. Moreover

with bigger widthes they can appear multiple problems of roof, carried forward alignment

etcetera. In order to protect the entrances to the slice and the initial front in which is localized

the whole equipment leaves a few good mud-runner pillars of a few 60 to 150 m of width in the

sense of the advance in both extremes of the slice.

Conclusions

To select a method of appropriate exploitation to a bed you are must keep in mind the different factors that have the beds

There are numerous methods for the extraction of so much minerals of superficial mining as subterranean