Açık işletmelerde uygun delme-patlatma şartlarını veren bir modelin geliştirilmesi

Abstract

Açık işletmelerde optimum delme - patlatma şartlarını veren bir modelin geliştirilmesi hakkında olan bu çalışmada önce araştırmaların yapıldığı şantiyeler ve yapılan performans ölçümleri anlatılmıştır. Bölüm 4' de önce delici makinalar detaylı olarak tanıtılmıştır. Sonra da kayaçların delinebilirliği konusu üzerinde durulmuş ve literatürde bulunan delme hızı bağıntıları darbeli delme ve döner delme için ayrı ayrı verilmiştir. Bölüm 5' de kayaçların mekanik ve fiziksel özelliklerini belirlemek için yapılan deneyler anlatılmış ve sonuçlar özetlenmiştir. Arazide N - tipi Schmidt çekici ile ölçümler alınmış ve laboratuarda tek eksenli basınç ve çekme, darbe dayanım, nokta yük ve sismik hız deneyleri yapılmıştır. Ayrıca, elastik modül ve yoğunluk değerleri ile kuvars miktarı da belirlenmiştir. Bölüm 6' da konili matkap dişiyle yapılan penetrasyon deneyi hakkında daha önce yapılan teorik ve deneysel çalışmalar anlatılmış ve yapılan penetrasyon deneyi yardımıyla döner deliciler için geliştirilen delme hızı modeli sunulmuştur. Bölüm 7' de çok katlı regresyon analizi anlatılmış ve üç tür delicinin herbiri için (yerüstünden darbeli hidrolik, delik dibinden darbeli ve döner delici) geliştirilen regresyon modelleri verilmiştir. Bölüm 8' de patlayıcıların teknik özellikleri, ateşleme eleman ve şekilleri detaylı olarak anlatılmıştır. Ayrıca patlatma teorisi açıklanmış ve kayaçların patlatılabilirliğine ve parça boyutuna etki eden faktörler sıralanmıştır. Bölüm 9' da basamak patlatması üzerinde durulmuştur. Basamak patlatmasında delik düzeni parametrelerinin birbirleri ile olan ilişkileri incelenmiş ve bu konuda literatürde bulunan bağıntılar verilmiştir. Sonra da ülkemizdeki uygulamaların bu bağıntılarla uyumlu olup-olmadığı araştırılmıştır. Bölüm 10' da delme - patlatma konusunda geliştirilen bir bilgisayar programı anlatılmıştır. Delme - patlatmadaki tüm işlemleri içeren program üç ana bölümden oluşmaktadır: Birinci bölümde, yükleyici ve basamak yüksekliği seçimi, delik çapı, delik düzeni, delici makina ve matkap seçimi yapılmaktadır. İkinci bölümde patlayıcı seçimi, yıllık patlayıcı miktarı ve ateşleme sistemi belirlenmektedir. Üçüncü bölümde ise delme-patlatma maliyet hesabı yapılmaktadır.

This study is about the development of a model to obtain suitable drilling and blasting conditions in open pit mines and quarries in Turkey. The study mainly contains insitu observation, obtaining drilling-blasting data, determination of the drillability characteristics of the rock samples collected from worksites, developing of a model to predict the rates for different drills, interpretation of the obtained blasting data and developing a computer model which comprises all processes from the selecting of the drill machine type to cost analysis of drilling and blasting operations. The drilling performance was measured on rotary drills, down the hole drills (DTH), and hydraulic top hammer drills at the different 16 worksites and 27 formations. Hydraulic top hammer drills were observed at different 4 sites and 14 formations. The model of top hammer drills observed are Böhler, Atlas Copco, Tamrock and Frukawa. DTH drills were observed at different 5 worksites and 7 formations. The model of DTH drills are Gemsa. Rotary drills were observed at different 6 worksites and 8 formations. The model of rotary drills are Ingersoll-Rand and Reedrill. The diameter of drill holes, the drilling and blasting patterns, and the type and amount of explosives were recorded during each field performance study. In chapter 4, after the drills are introduced in details, the drillability of rocks is given. The drills used in surface can be classified as rotary drills, top hammers and down the hole drills. The components of rotary drills are carrier, diesel or electric drives, mast, dry or wet dust collection system, electric, hydraulic or pneumatic rotation system, feed system, flushing system and drill bits. Top hammer drilling combines four functions: percussion, feed, rotation and flushing. Top hammer drills used in quarries and open pit mines are either pneumatically or hydraulically operated. Because, hydraulic drills have many advantages over the pneumatic type, the tendency has been towards hydraulic drilling for a number of years. Hydraulic top hammer mainly consist of rock drill, feed system, rod changes, control panel, boom, dust collector, crawler base and powerpack. Pneumatic crawler drills are normally equipped with light or medium-heavy crawler basis and the boom types available are fixed, articulated and telescopic booms. These drills are suited for xxn small construction worksites or quarries where the total amount of rock excavation is not very large. Due to the different advantages, one hydraulic drill can usually replace two to three pneumatic ones. DTH drills utilize the compressive air power in percussive drilling more efficiently than conventional pneumatic top hammer drills. A DTH hammer follows immediately behind the bit into the hole rather than remaining mounted on a feed as with top hammer drills. Therefore little percussion energy is dissipated in the pipe joints and the penetration rate is nearly constant. The drilling accuracy of DTH drills is good. DTH drills are commonly used in bench drilling of 89-165 mm drill holes on benches up to 50 m. The type of the drill which will be selected for a specific job depends on the output required, the hole diameter and the drillability of the rock. The drillability of rocks, is a function which depends chiefly on the hardness, abrasivity and mineralogy of the rocks and this will decide the appropriate type of drilling machine; percussive top hammer drills or DTH drills in hard to moderately hard formations, rotary drills in moderate and weaker sedimentary formations. The other factors affecting the choice of drill rig are bench height, fragmentation, terrain conditions and environmental restriction. Pneumatic drills are simple in construction, and easy to operate and service. Operators are used to these drills, but they are also used to high fuel consumption and low penetration rates. These drills are suited for small scale quarries and construction works. Automation and mechanization are relatively easy and affordable in hydraulic drills. So, it is possible to achieve a net increase in productivity of over 100 %. In percussive drilling the rock is mainly broken by individual impact and rotation between blows. Rotary drills break the rock with thrust and rotation. The drillability of rocks depends on many factors. Bit type and diameter, revolution per minute, feed, thrust, blow frequency and flushing are the parameters which can be controlled. On the other hand the parameters such as rock properties and geological factors can not be controlled. Thus several theoretical and empirical formulas have been developed for predicting drilling performance. These formulas are presented in chapter 4. In chapter 5, experimental works carried out to determine the mechanical and physical properties of rocks were explained. Schmidt hammer testing in the field, uniaxial compressive, indirect tensile (Brazilian), impact strength, point load and seismic velocity testing methods were applied on the rock specimen obtained from the site. Furthermore, the Young's elastic modulus, density and amount of quartz were determined. In chapter 6, the penetration mechanics of bit tooth were explained and the theoretical and experimental works given in literature were summarised. Then the penetration test carried out in Mining Faculty of ITU was described. A model based on Morris (1969) approach was developed with using of drillability index which is the slope xxiii of the characteristic force-penetration curve obtained from penetration testing. This model is only valid for the formations which has uniaxial compressive stregth of over 40MPa. Drillability index is affected by the tooth angle and the properties of rocks. When tooth angle, the magnitude of physical and mechanical properties of rocks increases, the penetration load increases. Therefore, drillability index increases. In chapter 7, multiple curvilinear regression analysis of drilling performance data was carried out using "Statgraphics" computer program. As drilling performance is affected by several factors which are especially rock properties and operational variables, drilling performance can not be studied using simple regression or graphical method. Therefore, multiple regression analysis must be used. Because, regression models which contain less variable is simple and practical, it should be decided to include which variables in to the model. In this study, "All Possible Regressions" method was used to decide which variables should be include in the model. The regression models for hydraulic top hammer, down the hole drill and rotary drill were developed. The selection criteria for the best model are:. Coefficient of multiple determination (R2). t test. F test. Residual analysis Regression analysis showed that the most significant parameters affecting rate of penetration for hydraulic top hammer model are blow frequency, uniaxial compressive strength and quartz content of the rock. Schmidt hammer value and the product of operational pressure and piston diameter were included in the model for DTH drills. Also, another model for DTH drills was developed in case the first model can not be used. Impact strength value and the product of operational pressure and piston diameter were included in this model. For the rotary drills bit diameter, weight on bit, revolution per minute and compressive strength were selected as the most significant parameters. In chapter 8, technical properties of explosives, initiation systems and blastability of rocks were presented. The technical properties of explosives used in surface are: Explosion strength and efficiency Easy detonation and sensitivity Oxygen balance Energy transfer ratio Safety Water resistance Storage properties Fume characteristics XXIV Explosives can chiefly be devided in two groups: dynamites and blasting agents. There are different types of dynamite: straight dynamite, ammonia dynamite, gelatin dynamite, semi-gelatin dynamit, and special dynamites. Although straight dynamites have high density, high velocity and fair water resistance, their industrial use and importance are declining, because of their high cost and excessive sensitivity. Ammonia dynamites have low to medium velocity of detonation and exhibit good heaving action due to the increased gas production. These dynamites are suited for weak and relatively soft ground. Most ammonia dynamites, however, have poor to fair water resistance and are thus limited in their use. Because of its highly gelatinous "rubberlike" consistency, straight gelatin dynamite has excellent water resistance. Ammonia gelatins have high densities and high velocities. Because of high energy output, they are particularly suited for shooting hard rocks. The semi- gelatin dynamites exhibit moderately high detonation pressure and an adequate amount of water resistance In addition these standard categories there can be numerous special requirements with in each general family. These include: Extra density, extra water resistance, extra velocity of detonation etc. Anfo offers great economy and safety in modern blasting applications. It generally costs one-third to one-half as much as nitroglycerin explosives and it is considerably safer to handle because of its lack of sensitivity. Anfo-type products generate low detonation pressure with good borehole that generally in good heaving action on throw of the burden. Generally speaking, anfo is one of the best types of explosives for blasting dry holes in excess of 5 1 mm in hole diameter, which are conductive to breakage by gaseous expansion. The primary disadvantage of anfo is its lack of water resistance; ones it gets in contact with water, it will no longer detonate. Heavy anfo which is a mixture of anfo and emulsion explosive is becoming more widely used, as it frequently as effective as pure emulsions and considerably cheaper. Slurries are especially suited for large hole blasting and wet conditions. They are cap insensitive and therefore need to be initiated with an explosive primer. Slurry contains ammonium nitrate, TNT, water and substance to keep the explosive homogeneous. The properties of any individual composition depend on the type and proportion of various solid ingredients. Because the density is greater than that of water (1.0-1.8 g/cm3) the slurry will sink to the bottom of a wet blasthole. The detonation velocity of slurries ranges from 3400 m/s to 5500 m/s. Emulsions are two phase products where by the dispersed phase is disseminated throughout a continuous phase. Explosive emulsions are mixture of fuel and oxidant components. The oxidisers are predominantly nitrates and the fuels mostly hydrocarbon of mineral or organic derivation. The increase in efficiency is reflected in the velocity of detonation, 5000-6000 m/s for emulsions compared with around 3200 m/s for anfo and 3300 m/s for slurry. This high velocity of detonation is one of the major advantages of emulsions as it provides high shock energy, a significant factor with hard rock. xxv Rock blastability is determined as the resistance of the rock to blasting, and it is mainly influenced by the rock properties and geological factors. In solid, hard rock blastings can be sufficiently well controlled, whereas in fractured rocks part of the energy explosive is lost in the cracks and blasting are not always controlled. Factors affecting rock blastability are:. Rock type contacts. Faults. Jointing. Bedding plane and schistosity. Dip and strike of rock formation The required fragmentation depends on the use to which the broken rock is to be put and on the equipment which is to handle it. For some purposes big boulders are preferable, but usually finer fragmentation is wanted. Several factors affect fragmentation, of which the following are the most important:. Rock characteristics. Blasthole straightness. Explosive properties. Loading of blastholes. Specific charging. Firing system In chapter 9, bench blasting was investigated and its position in Turkey was assessed. The parameters of the drilling pattern in bench blasting are bench height, hole diameter, subdrilling and drilling length, burden and spacing between holes. These parameters which depend on each other, rock type and characteristics, type of explosive and required grain size etc. were investigated in details and all formulas which are related with these parameters in literature were given. Then, the charging of holes was studied and the methods of charge calculation in literature were given. After that, the applications in Turkey were compared with the formulas in literature. Following results have been found:. Only the relation between burden and hole diameter is in conformance with the formulas given in literature. Other relations have inconformity or rarely conformity. This inconformity is due to the wrong selection of the parameters of the drilling pattern and the speciality of working conditions or requiring different fragment size from excavated material.. For open pits a linear relationship between compressive strength of rocks and specific charge and a conformity between applied and theoretical specific charge were found. There is no relationship between the strength properties of rocks and specific charge for highways and quarries. This is probably due to required fragment size frequently changes for especially highways and also specific charge changes in the result of fragment size changing. In the meantime a good conformity was not found between applied and theoretical specific charge. xxvi In chapter 10, a computer program developed for drilling and blasting was explained. The program mainly contains three parts. The first part is about drilling. In this part, the selection of loading equipment, bench height, hole diameter, drilling pattern, drill rig and bit is done. In part two, type of explosive is selected, explosive quantity per annual and firing system is determined. In the last part, drilling and blasting costs are calculated.