Pershin G.D., Karaulov N.G., Ulyakov M.S.

FSBEI HРE “ Magnitogorsk State Technical University

named after G.I. Nosov”

ANALYSIS OF GRANITE BLOCKS MINING TECHNOLOGICAL SCHEMES IN FINLAND, ITALY, PORTUGAL, SPAIN, AND RUSSIA

Multi-system natural solid mass fracturing, forming natural joints of different volume, is the peculiarity of the high – strength block stone deposits. In mining processing, saw cuts, forming artificially created joints, are imposed on the natural cracks of the solid mass. During the consequent cutting, blocks of regular geometric shape are obtained [1].

Granite blocks open cast mining method is realized according to three schemes: one-, two-and three-stage. The choice of one or another scheme depends on the size of the natural stone blocks solid mass, which are determined by fracturing index. Practically, in most cases the number of stages comprises two or three.

One -stage scheme provides the finished product obtaining after blocks separation from the solid mass (1-10 m³). Excavation of blocks shaped to a standard size is achieved with the help of this operation. At present, this scheme is seldom applied.

Two-stage mining is needed because of extractive blocks (monoliths) large size while using natural fracturing solid mass. In this case, monolith, separated from the solid mass differs from the required dimensions and should be cut into blocks of necessary size and shape.

Two-stage block mining technology consists of two steps: monolith of 80-800 m3 separation from solid mass and secondary cutting (Fig. 1).

Fig. 1. A two-stage scheme of granite blocks mining with monolith tipping: a - primary monolith separation of from the solid mass; b - monolith tipping on the damping filling ; c, d - marketable blocks monolith cutting

In Figure 2 the tipped monolith cutting by the blast-hole method with the mechanical wedges application in the granite quarry Luboiu (Italy) is shown.

Herewith a diamond wire machine is used to separate the monolith along the horizontal sheet (DWM).

a

b

Fig. 2. Quarry Luboiu. Sardinia (Italy): a - DWM horizontal cut, b - cutting of monolith tipped on the damping filling.

In case of longitudinal and cross crack systems are close to the vertical direction, and bed-sheeted crack bedding are horizontal or low-inclined (incidence angle up to 5 degrees), the separation is performed without tipping (Fig. 3).

Fig. 3. Two-stage scheme of granite blocks extraction without monolith tipping.

In Figure 4 a two-stage scheme of granite blocks extraction without monolith tipping at Mansurovsky granite deposit (Russia) is shown [2].

Fig. 4. Scheme of marketable blocks monolith separation and cutting without tipping at Mansurovsky granite deposit: 1 - loader, 2 - blocks, 3 - self-propelled drilling rig DC 120.

The main difference between a three-stage scheme from the two- stage scheme consists of the greater volume 300-3000 m³ monolith separation from the solid mass (Figure 5) [3-5].

Fig. 5. Three-stage scheme of granite blocks extraction with monolith tipping and cutting in the parallel or orthogonal direction to the crack system ( Lower Sanarskoe granodiorite deposit, Russia):

a - primary monolith separation (10 * 6.8 * 5 m), b - secondary monolith cutting (10 * 1.7 * 5 m), c - secondary monolith charging on the damping filling and its division into blocks (1.7 * 1.2 * 1.5 m)

The process selection of stone volume extraction preparation by three-or two-stage scheme is realized dependently on the bench height, its component layers number and working sites possibilities for monolith carving into marketable blocks. According to the technology under consideration, initially large monoliths are separated from the bench. The monolith length can reach several dozen meters, and is divisible, as a rule, to the distance between jointing cross cracks in the monolith faces. The large monolith width should be a divisible value to the marketable block length or width. Further, a great monolith is divided into smaller units in the longitudinal or cross directions, which is the second stage of preparatory work. Secondary monolith as well has dimensions divisible to the marketable block basic size. Then, there is a third stage, when taking into account the bench height horizontal layers, marketable blocks are obtained from the secondary monoliths.

Geometrical parameters, shape and quality of blocks mined abroad do not correspond to the Russian ones. The minimum dimensions of commercial granite blocks from abroad are 2.5 m³, while in our country blocks even less than 0.5 m³ are in the processing. In Spain and Italy, many of mined blocks are stored in warehouses for a long time because of excess. In Russia, on the contrary, because of their lack enterprises can not use their full capacity. Many stone treatment plants have to buy imported granite blocks.

The amount of employed in the European quarries is 3-9 people. This is explained on the one hand by high-performance equipment application, and on the other hand by the lack of security, staff engineers excess and occupation combination. Over and above the equipment maintenance is carried out under “ third party services” provision.

In Russia engineer staff is inflated, because of Soviet officialdom traditions, and the number of permissive documents breaks all the world records. Everyone has to be responsible for something, but the traumatism does not reduced, but it is more than in European countries.

Two techniques of high-solid rock mining are primarily used abroad: Finnish and Spanish.

Further we shall consider the examples of their typical deposits [6]. Kuru Grey (Finland) and Rosa Porrino (Spain) quarries are of greatest interest.

Granite deposit Kuru Grey (Fig. 6) is located near the city of Tampere (Finland) and has been mining since 1950. With an annual output of 4,500 marketable blocks only three people work there: a loader driver, self-propelled drilling rig DC 120 and manual jackhammer operators. They also may perform other work.

It turns out that one mining worker has 1500 m3 of marketable blocks per year, while the highest rate in the Russian granite quarries (Mansurovsky, West Sultaevsky) is 200-300 m³.

Fig. 6. Kuru Grey Granite deposit (Finland)

The deepen-solid exploitation system is block mining by horizontal and slightly inclined beds-benches. Separated monolith parameters are the following: the optimal length is 40-60 m, height 1.2 m, width 1-1.5.

Cut slot is formed by Sandvik drilling rig (boring rig Sandvik DC 700, equipped with hydraulic hammer drill HL710, drilling depth up to 29 m, holes diameter from 64 up to 102 mm is recommended). Carrying through the cut slot they firstly drill by bits of 89 mm diameter, then of 76 (smaller diameter provides rational drilling-in). With the help of self-propelled drilling rig DC120 (drilling depth is up to 9 meters, the holes diameter is 24-45 mm, equipped with hydraulic hammer drill HEX1) holes of 24 mm in diameter with an interval of 30 cm are drilled. The deposit was prospected by two external and internal common trenches with a trace of spiral shape without contiguity. Ramps in quarries are as bulk as well as constructed in the granite solid mass (using natural bed-sheeted cracks). Drilling with a hand held hammer drill is used to prepare the quarry benches.

WA600 loader (Fig. 7) produced by Komatsu with a bucket capacity of 6.5 m³ is additionally equipped with quick-detachable pitchfork and blocks tilter for monoliths tipping on some bulk bedplates from chip and bore meal. The separated blocks are transported by loader to the temporary store house which is located in the quarry worked-out area.

Fig. 7. WA600 loader block transportation

The technology also provides primary monolith explosive separation by Forsit tubes. Detonation occurs consistently partially and, therefore, this rock blasting method does not affect the stone modularity.

Rosa Porrino deposit (Fig. 8) is located in the north-western Spain near Porrini. This upland deposit, with the lack of loose stripping, has been developing since 1960. At present, the number of employees comprises 9 people, 4 of them are detached by a customer.

With a marketable blocks capacity of 12,000 m³ per year 1,333 m³ comes to one worker.

Fig. 8. Rosa Porrino granite deposit (Spain).

High-benched three-stage technology of DWM blocks mining is used at the quarry.

Sawing is carried out by quarry machines CBC75HPN (power 55 kW, the diameter of the drive pulley 810 mm) and CBC-MD75HP (57 kW, 810 mm) produced by the Spanish company Grani Roc (city of Leon), which is the part of Grupo Hedisa Cor (Fig. 9).

Fig. 9. Diamond wire machine SHS 75 HPN

(produced by Grani Roc)

Maximum sawing productivity reaches 10 m² / h. It is noteworthy that at the end of the working day in the absence of people diamond wire machines are left running. Water for wire cooling is not reused. Long hole drilling machine (pneumatic, crown diameter of 90 mm, produced by Grani Roc company) provides pilot boreholes drilling. Horizontal borehole is at height of 10-20 cm from the surface of the mining floor. The main reason of the actual performance lag from the designed is the complexity of the pilot boreholes docking and, as a consequence, small equipment utilization coefficient. Due to the probe use for holes prospecting (Grani Roc) the process of docking becomes much easier and takes less time. Stitch drilling rig COF-2 is applied in the secondary monolith cutting (height 15 m, length 30-40, width 1.5 m). It is equipped with two pneumatic drilling hammers with expected technical performance of 0.6 m / min, produced by Grani Roc company. There is a fixed distance of 30 cm, set by the manufacturer between drilling hammers. Holes are drilled with a diameter of 32 mm with 15 cm section. Mechanical wedges and pneumatic hammer is used to separate blocks. Finished blocks are loaded in trawl and transported to the store house (transportation distance is about 400 m). Two loaders work at the quarry: CAT 988 F (6.5 m³ bucket capacity), CAT 988 B (8 m³ bucket capacity). The secondary monolith tipping is performed with the use of hydro bedplates.

A compressor (produced by Atlas Copco company) is foreseen for stitch drilling rig installing and a diesel generator is foreseen for diamond wire machines operating. Expanding powders similar in composition to the LDCs (ICOLD) - Masa Expansiva produced by Sumi Roc (Grupo Hedisa Cor) are also used at Spain granite quarries. The maximum spacer force from the powder and water mix arises after 24 hours.

Having analysed the best granite deposits developments in Finland, Italy, Portugal, Spain, Russia and literature sources we can make the following generalizations.

The acquaintance with foreign experience of highly solid stone mining allowed to get known the market requirements for block quality.

These requirements are completely incompatible with Russian regulatory acts (GOST 9479-2011).

The research and experience of the diamond wire application shows the high wire wear when high strength stone cutting. Due to the high consumption of diamond tools on solid rock and its high cost it is advisable to use diamond wire cutting in combination with a borehole way of monolith separation. [6].

The analysis [1-7] showed that the following operations in the monolith separation from the solid mass are used:

– horizontal cut with diamond wire cutting using;

– vertical cross sawing cut is produced with the diamond wire;

– vertical longitudinal sawing cut with the use of diamond wire cutting or borehole method with special hose or hydro wedges (рис. 10).

or:

– sawing cut in the vertical, longitudinal and cross sheets is performed using diamond wire machine;

– creation of horizontal separation sheet using the borehole method with special hose.

Diamond sawing horizontal cut is carried out at an angle of 2-4 degrees deep in the solid mass to get the opportunity for the water supplying to the wire with a stone contact point. Water can be also supplied under pressure along the vertical wellbore.

a

b

Fig. 10. Prugnola quarry on island Sardinia (Italy): a - the use of a drill borehole way to create a vertical longitudinal cuts, b - the creation of horizontal separation by a drill borehole way

In each case, the combination of diamond wire sawing cut and borehole way of the monolith separation will be conditioned by the naturally massif fracturing, provided the lowest operating costs for the stone volume preparation to excavation.

Cutting monolith in marketable blocks are usually carried by a borehole way with different gripper systems and should take into account the natural form joints making up the monolith.

The presented data indicate the need of the rational way choosing to prepare blocks for excavation for the specific conditions of development. Equipment, singly chopped out of the Finnish or Spanish mining scheme, purchased for our enterprises, does not affect the productivity increasing in block production within the accepted technology in Russia.

References

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2. Pershin G.D., Pshenichnaya E.G., H. Hasanov H. F., Ahabzyanov R.M. Extraction improving of blocks mining at Mansurovsky granite deposit // Mining, processing and use of natural stone: Collection of scientific articles - FSBEI HРE “Magnitogorsk State Technical University named after G.I. Nosov”, 2009. - S. 4-17.

3. Sinelnikov O.B. Natural facing stone mining. - Moscow: Publishing House of Agricultural Sciences, 2005. - 245 p.

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5. Tarasenko A.V., Kondratyev L.A., Saveliev G.P. Diamond wire machines opening of underlying horizons at the granite quarry of the East Varlamovskogo deposit // Stone around us. - 2009. - № 21. - Pp. 25-29.

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7. Karasev U.G. Mining methods for facing stone quarries. - Moscow: Nedra, 1995. - Pp. 21, 22.