Metal Madenciliğinde Yeraltı Açıklıkları İçin Macun Dolgu Malzemesinin Araştırılması

Abstract

Günümüz madenciliğinin en büyük problemlerinden biri olan atık bertarafı birçok ekonomik ve çevresel olumsuzluklara neden olmaktadır. Özellikle metalik sülfürlü cevherlerin üretimi sonucu sülfür içeriği yüksek atığın meydana geldiği durumlarda, su ve oksijen varlığında sülfürlü minerallerin oksidasyona uğraması, asidik su oluşumuna ve atık içindeki metallerin çözünmesine neden olarak çevre kirliliğine yol açmaktadır. Bunun yanısıra atıkların yeryüzünde veya deniz derinliklerinde depolanması ekonomik olarak maden şirketleri için külfet olmaktadır. Günümüzde nispeten yeni ve kullanımı Avustralya ve Kanada’da yaygın olan, macun dolgu sistemi yardımıyla, atıklar yer altında kontrollü bir şekilde depolanabilmektedir. Bu sistem sayesinde atıkların tamamına yakını çevre kirliliğine yol açmadan yeraltına güvenli bir şekilde yerleştirilmektedir. Ayrıca macun dolgu sistemi yeraltında güvenli çalışma ortamları sağlaması ve yeryüzündeki meydana gelen tasman hareketlerini en aza indirmesi açısından da büyük önem arz etmektedir. Tanım olarak macun dolgu, cevher hazırlama tesisinden atık olarak elde edilen ve pasa olarak da adlandırılan, sınıflandırılmamış tesis atığının, macun dolgu tesisinde belirli oranlarda su ve bağlayıcı maddeler eklenerek karıştırılması sonucu oluşan ve yeraltı boşluklarını doldurmaya yarayan homojen dolgu malzemesidir. Macun dolgu içeriğini %70-85 arasında atık, su, bağlayıcı ve kimyasal katkı maddeleri oluşturur. Eczacıbaşı ESAN’a ait Balya Kurşun-Çinko madeni tesis atığının macun dolgu olarak kullanılabilirliliği üzerine araştırmalar bu çalışma kapsamında gerçekleştirilmiştir. İlk olarak atığın fiziksel, kimyasal ve mineralojik özelliklerini belirlemek amacıyla piknometre, tane boyut dağılımı, Atterberg limit deneyleri ile XRD ve XRF gibi deneyler yapılmıştır. Daha sonra atığın yeraltında dolgu malzemesi olarak kullanılabilirliliğine ilişkin olarak, laboratuvar ortamında 12 farklı reçeteye bağlı karışımlar hazırlanarak 340 adet numune hazırlanmış ve dolgu malzemesinin mekanik özellikleri araştırılmıştır. Bu araştırmanın temel amacı, macun dolgu olarak kullanılması düşünülen atığın yeraltı açıklıklarının doldurulmasında başarılı bir şekilde uygulanabilirliğinin anlaşılmasıdır. Farklı kür süreleri sonucunda dolgu malzemeleri üzerinde tek eksenli basınç dayanımı ve elastik modül deneyleri gerçekleştirilerek yeraltında uygulanabilir en uygun karışımın tasarımı yapılmıştır. Buna ek olarak macun dolgu kullanılan maden işletmelerinden uyarlama yaparak örnek macun dolgu tesisi planlanmıştır.

Nowadays, waste disposal which is the most crucial problem for mining leads to not only environmental, but also economical problems. Especially, the high sulfur content of waste from the production of metallic sulphide ores causes environmantal pollution. Moreover, storage of waste in the depths of the earth or the sea is the economic burden for mining companies. Last three decades, waste can be stored in the ground in a controlled manner by pastefill which is common to use in Australia and Canada, even though it is a relatively new system. The main purpose of this study is the understanding of applicability of the pastefill which is used to fill underground openings successfully. In the underground metal mining, paste fill which consists of dimensionless waste of mineral processing plants, waste of power plants, sand or aggregate, water, binders and various chemicals is a mixture of fluid consistency. Definition of pastefill according to Brackebusch is typically a low permeability, high density solids mixture of aggregate solids and water containing at least 15% by weight fines material at sizes ranging between minus 20 μm to 45 μm content. Pastefill is created %70-85 of waste, water and chemical addictives. Generally, portland cement is used as a binder in the mixture of paste fill. If the rate of sulphate which leads to reduct the long period performance of paste fill is high, sulphate resisting portland cement should be used as a binder. Artificial or natural pozzolans such as fly ash can be used in the mixture of paste fill as a binder so as to decrease the cost of cement, because it is the most vital part of the operating cost. Through this system, almost all waste can be disposed underground safely without causing environmental pollution. In addition, underground paste backfill system to provide safe working environments and minimize the movement of the earth subsidence occurred. Field of study operating in a Lead-Zinc Mine belongs to Eczacibasi Group in Balya, Balıkesir. According to offical records, the area of mine is 2.900 hectares. Mining operation in Balya Lead-Zinc Mine began production in 2009. Average 240.000 tons crude ore are producted per year. 30.000 tons of crude ore is proucted as a ore concentrate. The samples of Balya Metal Mine on bright sections under a microscope show that respectively galena, pyrite, sphalerite, chalcopyrite, tetrahedrite, magnetite, pyrrhotite, stibnite, rsenopyrite, boulanjerit, jamesonit, bismutite can be seen. Amount of galena, which is the most common matel in that mine, increases towards the upper levels. The result of researches, proven and probable reserve of lead and zinc are calculated as an approximately 3.043.300 tons. Average grade is calculated as 9,1%. Sublevel filling Method is applied to the western galeries. Ore which is seperated by 15 meter pieces is produced by 5 meter slices. 35-meter galeries are excavated so as to get 5-meter vertical distance. All excavated galleries are filled with fillers. When the production of ore is completed in these galleries, if there is another gallery under these galleries, these galleries are filled with 8% filler. Depending on the width of the ore, if a gallery will be excavated next to the completed gallery, completed gallery are filled with 6% filler. If there are not any gallery next to the completed gallery, completed gallery are filled with waste or is not filled. Transportation of the ore which is blasted is maintained by shovels and trucks. Ore arrives from underground to surface approximatly 30-45 minutes. Shotcrete and rock bolt (split set) are used in Balya Lead-Zinc Metal Mine in order to increase the resistance of the floor and prevent probable accident. There is a mineral processing plant in Lead-Zinc Mine. That plant is used for flotation of lead and zinc. An excavated ore is tranported with the band to the crushers. A jaw crusher and two cone crushers are used in order to crush. Two ball mills are used for grinding. This thesis is about the availability of the plant waste for using pastefill material. First of all, 2 different wastes were transported from Balya Metal Mine to the Rock Mechanics Laboratory at Mining Faculy in Istanbul Technical University. Next step is to define characteristics of these wastes. Grain size distribution tests were done for 2 different wastes multiple times so as to determine physical characteristics of them. Average value of these tests are demonstrated in this thesis as size distrubition graphics. Likewise, pycnometer tests were done for them 5 times in order to determine their density. Moreover, Atterberg Limit Tests, such as Liquit Limit and Plastic Limit Tests, were done so as to realize their physical behaviour. All of those tests were done at Rock Mechanics Laboratory of Mining Faculty in Istanbul Technical University. All results of those experiments are shown at tables in this thesis. Besides determining physical characteristics, some experiments were done in order to determine chemical characteristics of 2 different wastes at Geochemistry Laboratory of Mining Faculty in Istanbul Technical University. XRF experiments were conducted so as to determine their chemical characteristics multiple times. Average value is shown on tables. Furthermore, XRD tests were conducted for 2 different wastes to investigate their minerological properties. Results of tests are shown as graphics in this thesis. After determining physical, chemical and minerological characteristics by experiments, 12 different prescriptions were prepared for each wastes. Every prescription has a different cement ratio and slump value. Totally 24 prescriptions were prepared and also 5 different curing time were decided, respectively 7, 14, 28, 42 and 56 days. Then, 340 mixtures were prepared depend on 24 different prescription in order to investigate mechanical properties and determine Uniaxial compressive stress tests results and elastic modulus. Thus, it can be designed the most suitable mixture depends on prescriptions. Before preparing specimens, all waste were dried with drying oven for 24 hours at 105°C. After that, waste, cement and water were weighed with balance. Then balanced materials were mixed with mixer until having a homogeneous mixture. After that, all homogeneous mixtures were tested so as to determine slump value. If the slump value is suitable for prescription, these mixtures are filled with scoop in a sampling vessel. Before filling pastefill into the sampling vessel, sampling vassel must be lubricated. Before curing time, sample must take out from the sampling vessel in order to prepare Uniaxial compressive stress test. All samples were encoded one by one. Before the uniaxial compressive stress tests, all samples were capped with cyclinder capping test set. Capping materials are mixtures of 70% sulphur and 30% graphite. These mixtures were prepared in a melting pot. After capping, at the end of the appropriate curing times, all samples were done Uniaxial compressive stress tests with a stiff test machine. After these experimental studies, results are demonstrated as graphics with the help of the Ms Excel and also all results are shown as tables. Before and after the tests, photos of samples were taken for archieving. At the end of the 340 tests, the best prescription was chosen depends on the results of stiff test machine. Furthermore, pilot pastefill plant is design by some metal mines in the world which are used pastefill system. Some machines are neccessary for preparing pastefill such as storage mechanism, dewatering equipments ( cyclones and filter disks), weight belt, fluidization silo, mixer and mixing screw, binder silo ,hopper, pump mechanism – pipeline – borehole. All machines must be new technology. Pastefill should checked after preparing it with quality control system. Quality control is so vital for pastefill system. Lack of this system might lead to some problems such as wrong paste concentrations, barricade problems and transportation problems. Even though pastefill system has some drawbacks, its advantages outweigh its disadvantages. For example, although capital cost of pastefill is expensive, operating cost of pastefill is cheaper than other systems. If we think about processing for five years, cost of pastefill will be cheaper than other filling system and storage of waste on surface. Binder content can also be reduced with pastefill system. Moreover, almost all waste can be disposed underground safely without causing environmental pollution. It can be clearly seen that pastefill is both an environmental friendly system and also beneficial economically for mining industry. Pastefill system will be more economic with the help of the advanced technology. Therefore, scientists should make more reseach about pastefill system.