TAMBANG BAWAH TANAH

Tambang bawah tanah mengacu pada metode pengambilan bahan mineral yang dilakukan dengan membuat terowongan menuju lokasi mineral tersebut.Berbagai macam logam bisa diambil melalui metode ini seperti emas, tembaga, seng, nikel, dan timbal.Karena letak cadangan yang umumnya berada jauh dibawah tanah, jalan masuk perlu dibuat untuk mencapai lokasi cadangan. Jalan masuk dapat dibedakan menjadi beberapa: Ramp, jalan masuk ini berbentuk spiral atau melingkar mulai dari permukaan tanah menuju kedalaman yang dimaksud. Ramp biasanya digunakan untuk jalan kendaraan atau alat-alat berat menuju dan dari bawah tanah. Shaft, yang berupa lubang tegak (vertikal) yang digali dari permukaan menuju cadangan mineral. Shaft ini kemudian dipasangi semacam lift yang dapat difungsikan mengangkut orang, alat, atau bijih. Adit, yaitu terowongan mendatar (horisontal) yang umumnya dibuat disisi bukit atau pegunungan menuju ke lokasi bijih.

Ada dua tahap utama dalam metode tambang bawah tanah: development (pengembangan) dan production (produksi). Pada tahap development, semua yang digali adalah batuan tak berharga. Tahap development termasuk pembuatan jalan masuk dan penggalian fasilitas-fasilitas bawah tanah lain.Sedang tahap production adalah pekerjaan menggali sumber bijih itu sendiri. Tempat bijih digali disebut stope (lombong). Disini uang mulai bisa dihasilkan.

Dengan semua pekerjaan yang dilakukan di bawah tanah dengan panjang terowongan yang mencapai ribuan meter, maka diperlukan usaha khusus untuk mengalirkan udara ke semua sudut terowongan. Pekerjaan ini menjadi tugas tim ventilasi tambang.Selain mensuplai jumlah oksigen yang cukup, ventilasi juga mesti memastikan agar semua udara kotor hasil pembuangan alat-alat diesel dan gas beracun yang ditimbulkan oleh peledakan bisa segera dibuang keluar. Untuk memaksa agar udara mengalir ke terowongan, digunakanlah fan (kipas) raksasa dengan berbagai ukuran dan teknik pemasangan.Untuk menjaga kestabilan terowongan diperlukan pula penyangga-penyangga terowongan. Berbagai metode penyanggaan (ground support) telah dikembangkan. Penyanggaan yang optimal akan mendukung kelangsungan kinerja dan juga keselamatan semua pekerja.Berikut adalah daftar beberapa tambang terdalam di dunia: TauTona dan Savuka, tambang emas di Afrika Selatan yang merupakan tambang terdalam di dunia dengan kedalaman lebih dari 3.700 m. Xstrata Kidd Mine, tambang tembaga dan seng di Canada merupakan tambang terdalam di Amerika Utara dengan kedalaman 2.682 m. Mount Isa, tambang tembaga, dan seng di Australia dengan kedalaman 1.800m.

Faktor-Faktor Yg Mempengaruhi Pemilihan sistem tambang Bawah Tanah :

1. Panjang Tebal dan lebar cebakan.Berpengaruh utk menentuikan dimensi stope maksimum yaitu yg dikenal sbg minimum stoping width.

2. Kemiringan CebakanMenentukan kemungkinan memanfaatkan gravitasi dlm operasinya.

3. Kedalaman OperasiRock Failure mjd lebih memungkinkan pd kedalaman yg besar.

4. Faktor waktuBerpengaruh pd strenght stress ratio pd exposed rock. Semakin lama waktu pilar berdiri mk ssr semakin turun

5. Kadar cebakanCebakan kdr rendah perlu met produksi besar yg sering melupakan %tase recovery, ceb kdr tinggi memerlukan met yg menjamin recovery tinggi.

6. Fasilitas lokal yg meliput buruh dan material.Biaya buruh mahal mk memerlukan met yg mpy mekanisme tinggi. Ketersediaan timber dan material filling juga berpengaruh.

7. Modal yg tersedia.Modal kerja awal besar mk biaya operasi rendah. Perusahaan dgn modal kecil memerlukan development yg murah dan metode yang cepat mendapatkan hasil.

8. Batas dgn badan bijih lain.Tingkat tegangan yg tinggi mungkin timbul pd pilar di perm kerja yg berdekatan mk diperlukan filling pd stope bekas penambangan utk mengurangi tegangan yg tinggi.

9. Strength dan karakteristik phisik bijih dan batuan ddg atau material yg berada di atas bjh.Berpengaruh pd kompetensi, amblesan, kemudahan pemboran, karakteristik breaking, cara handling, ventilasi dan pemompaan.

Karakteristik-Karakteristik tsb termasuk :Tipe batuan, tipe dan penyebaran alterasi, weaknesses seperti (perlapisan schistocity belahan min patahan jointing cavities dan spasi),weaknesses sepanjang ddg cebakan, kecenderungan min berharga menghasilkan rich fines atau mud, kecenderungan BO utk memadat/menggumpal, kecenderungan BO teroksidasi dan terbakar, Terjadinya swelling pd lantai, Abrasiveness, terdapatnya air porositas dan permeabilitas cebakan dan bat sekitarnya.

10. Biaya Penambanganberkaitan dgn nilai bijih yg di Tambang, periode modal kerja bisa diperoleh kembali, tipe keahlian buruh yg tersedia.

11. ProduktivitasDinyatakan dlm ton per man shift yaitu menyatakan kemampuan setiap tenaga kerja menghasilkan BO setiap gilir kerja.

12. Masalah LingkunganKeamblesan, berkurangnya hutan lokal utk penyanggaan, kualitas dumpsite dll.

Sistem-Sistem Tambang Bawah Tanah:Stope dgn penyanggaan alamiah:- Open stope dgn underhand stoping- Open stope dgn overhand stoping- Open stope dgn breast stoping (room and pilar)- Sublevel stoping

Stope dgn penyanggaan buatan:- Cut and fill stoping- Shringkage stoping- Square-set stoping- stull stoping- longwall mining- undercut and fill- top sliocing

Metode caving:- Sub level caving- Block caving

Open stope alamiah:- Cebakan dgn bijih dan dinding yg kuat, kecuali pd ceb yg tipis yg datar/ sedikit miring dimana dpt di Tambang dgn sistem mundur- Penyangga brp bijih shg bijih tdk dpt diambil.- Penambangan scr selektif- Pd cebakan datar, dimungkinkan melakukan sortasi bijih di bwh tnh, sedang utk steep dip sortasi dilakukan scr terbatas- Terbatas pd cebakan tabular dgn btk teratur, ddg batas jelas ttp bias juga utk cebakan besar, menggumpal, irregular.

Open Stope Underhand stopingAplikasi:- End dgn tebal 3-4 m- Dip 50 yg memungkinkan memanfaatkan gravitasi pd pemindahan bo- Sbg metode keuntungan utk menganbil badan bjh yg terpisah dr bb utama atau bag dr bb utama yg memberikan kondisi yg cocok.- Hangingwall dan footwall kompeten utk mengurangi pemakaian ore pilar.- Bjh boleh tdk kompeten krn akan mjd tempat berpijak pekerja.Keuntungan :- Unjuk pemboran baik.- Perlu material penyanga sedikit- Memanfaatkan g untuk memindah broken ore- Pemboran ke arah bawah- Kehilangan bjh halus kdr tinggi < dibanding overhand stoping. Kerugian : - sorting sukar di dlm stope - Kondisi kerja berbahaya bg pekerja di back dan wall shg interval level hrs kecil - Fasilitas utk waste kecil - BO dr pemuka kerja dikeluarkan pd 1 ttk pengeluaran shg Output terbatas. Open Stope Overhand Stoping: Aplikasi: - Endapan dgn tebal 3-4 m - Dip 50 yg memungkinkan memanfaatkan gravitasi pd pemindahan bo - Sbg metode keuntungan utk menganbil badan bjh yg terpisah dr bb utama atau bag dr bb utama yg memberikan kondisi yg cocok. - Hangingwall dan footwall kompeten utk mengurangi pemakaian ore pilar. - Bijih kompeten - Pd urat dgn kemiringan besar >50 pekerja tdk bias berdiridi footwall shg perlu membuat platform utk berpijakKeuntungan :- Pos back tdk bahaya krn penambangan mengikuti back shg interval level bisa > dibanding open stope underhand stoping- Sorting sistematis- Waste mudah ditumpuk pd daerah tambang- Kondisi kerja aman, kondisi aplikasi elatis- pd kemiringan yg kecil Bro ore jatuh pd haulage drive scr gravitasiKerugian :- Unjuk pemboran turun- Dip > 45 diperlukan patform utk berpijak- Material penyangga banyak- kehilangan bjh uk hls kadar tinggi lebih besar

Open Stope Breast stoping (Stop and Pillar):Aplikasi:- Cebakan tdk bernilai tinggi yg mengijinkan sejumlah bijih ditinggal sbg pilar- Ketebalan < 7m - Cebakan > 7 m mungkin ditambang ttp loss bjh dan atap runtuh semakin besar- Dip 20-50: horizon mining yaitu stope n pillar yg diterapkan utk cebakan mendatar/ hampir datarinclined : 20 30, penambangan searah kemiringan dan tdk memungkinkan pemakaian mobile equipment step mining : 30-50, penamabangan scr berurutan utk menghasilkan daerah kerja dgn kemiringan yg memungkinkan menggunakan mobile equipment.- Batuan atap dan lantai kuat, utk meminimalkan pemakaian pilar- Bijih hrs kuat utk mengurangi lebar pilar- Kedalaman tdk terlalu besar utk mengurangi beban yg harus disangga pilarKeuntungan :- biaya rendah- memungkinkan seleksi pd stope dan waste ditinggal pd ruang kosong- memungkinkan melakukan mekanisasi dr drilling sampai loading dgn used trackless- development cepat dan dev dilakukan pd bijih itu sendiriKerugian :- kehilangan bijih pd pilar sampai 40% jk dgn pilar robbing mjd 20%- Bahaya runtuhan dr hanggingwall, dan bila hangingwall mpy joint dan crack yg sejajar memungkinkan runtuhan slab bat yg besar.- Daerah ventilasi sangat luas.

Sublevel stoping:Aplikasi:- dip 50-90 (steeply) yaitu kemiringan fw> drpd sudut gelincir bo - hanging dan fotter hrs kompeten- bjh hrs kompeten- bjh dgn batas penyebaran kadar merata- bjh sulfur butuh penanganan flotasiKeuntungan :- mengurangi drilling delay utk peledakan,scaling, mucking- pemb scr kontinue pd dev.- Longhole driller dpt diledakan di seluruh stope utk give bro ore yg banyak.- Fleksibel- Aman dr kebakaranKerugian :- tdk mungkin melakukan sorting scr efektif- blok bro ore besar bisa menyumbat grawpoints- ventilasi susah- rongga yang besar- losses dan dilusi besar- memerlukan periode yg lama sblm stope berprod

Stope dgn Penyangga BuatanCut and fill Stoping:Aplikasi:- utk menggantikan sublevel stoping dan shrinkage stoping pd penambangan yg sangat dlm dimana tegangan batuan mjd sangat besar.- batubara kompeten- hanging dan foot boleh tdk kompeten mengingat mereka akan hampir scr lanmgsung disangga dgn material filling- bjh dgn batas yg tdk teratur dan bjh yg discontinue, mk dilakukan penambangan pd bijih kadar tinggi dan meninggalkan bijih kadar rendah sbg filling- utk mengambil pilar kadar tinggi- dip tinggi dibanding shringkage dan sublevel stoping- ventilasi mudah diatur- dilusi seminimum mungkin- dinding antara 2 stope yg berdekatan bias lebih tipis disbanding metode stoping yg lain- stope fleksibel mengikuti ceb sempit kadar tinggi- stope stabil krn ddg yg lemah disangga dgn waste fillingKerugian :- butuh material filling mahal- butuh buruh banyak utk menangani filling- butuh banyak air utk pulp- lebih mahal disbanding shrinkage dan sublevel stoping- semen dan psr halus utk filling bias menyumbat pompa/pipa- output dr stope terbatas krn adanya kegiatan filling

Keuntungan Sublevel thd sringkage:- resiko kebakaran < pd penambangan cebakan sulfida- konsumsi bhn peledak < krn bijih lepas akan lebih terdisintegrasi pd saat bergerak dlm stope- kondisi penerapan sublevel stoping lebih fleksibel- sarana memasuki pemuka kerja lebih mudah- pekerja sedikit, pemboran efisien dgn longhole drill.

UNDERGROUND MININGUnderground mining refers to methods of making a mineral that is done by making the tunnel leading to the location of the mineral.Various kinds of metals can be retrieved through this method such as gold, copper, zinc, nickel, and lead.Due to the location of reserves are generally located well below ground, driveways need to be made to reach the location of the backup. The driveway can be divided into several: Ramp, this driveway spiral or circular start from the ground to the depth in question. Ramp typically used for road vehicle or heavy equipment to and from the underground. Shaft, which form holes upright (vertical) were excavated from the surface to the mineral reserves. Shaft is then fitted with some kind of lift that can be used to transport people, tools, or ore. Adit, namely tunnel (horizontal) are generally made hill or mountain side to the location of the ore.

There are two main stages in the method of underground mining: development (development) and production (production). At this stage of development, all of which are excavated rock worthless. Stages of development including the creation of the driveway and excavation of underground facilities other.Moderate stage of production is the work of digging the ore source itself. The place is called stope ore excavated (stope). Here, the money began to be produced.

With all the work being done in the basement with a long tunnel that reaches thousands of feet, it would require a special effort to draw air into every corner of the tunnel. This work is the duty of the mine ventilation team.In addition to supplying sufficient amount of oxygen, ventilation must also ensure that all the results of dirty air tools diesel exhaust and toxic gases generated by the blasting could soon be dumped out. To force the air to flow into the tunnel, is used fan (fan) giant with a variety of sizes and mounting techniques.To maintain the stability of the tunnel is also necessary props tunnel. Various methods of buffering (ground support) has been developed. Buffering will support the optimal performance and safety of all workers.Here is a list of some of the deepest mines in the world: TauTona and Savuka gold mine in South Africa which is the deepest mine in the world with a depth of over 3,700 m. Xstrata Kidd Mine, copper and zinc mine in Canada is the deepest mine in North America with a depth of 2,682 m. Mount Isa, mining copper, and zinc in Australia with a depth of 1.800m.

Factors Influencing Selection In The Underground mining systems:

1. Term Length and width of the mineral deposit.Influential menentuikan For maximum stope dimensions are reputed minimum stoping width.

2. Slope depositsDetermine the possibility of using gravity within its operations.

3. Operating DepthRock Failure mjd more likely that large depth pd.

4. Factor futureEffect of stress ratio pd pd strenght exposed rock. The longer the time the more ssr mk pillars stand down

5. Levels of depositsDeposits low kdr need large production meth oft forgotten% tage recovery, high kdr ceb meth requires that guarantee high recovery.

6. Facilities that cover local labor and materials.Expensive labor costs mk mpy mechanism that requires meth high. The availability of timber and filling materials are also influential.

7. Capital are available.Large initial working capital mk low operating costs. Companies with small capital development requires that cheap and quick method to get the result.

8. Limit with other ore bodies.High voltage levels which may arise pd pillars in perm work that needed filling pd mk adjacent stope mined For reducing the voltage that high.

9. Strength and physical characteristics of ores and rocks DDG or material that is above bjh.Influential pd competence, subsidence, ease of drilling, breaking characteristics, ways of handling, ventilation and pumping.

TSB Characteristics include:Rock types, alteration types and deployment, such weaknesses (schistocity bedding cleavage fracture jointing min cavities and spaces), along DDG deposits weaknesses, tendencies min valuable produce rich fines or mud, the tendency BO For condense / clumping, BO tendency to oxidize and burn, Occurrence swelling pd floor, Abrasiveness, the presence of porosity and permeability of water deposits and bat around.

10. Fee Miningvalue associated with antecedent ore mine, period working capital could be recovered, the type of the available labor skills.

11. ProductivityIndicated tonnes per man shift within which express the ability to generate any labor BO every working shifts.

12. Environmental IssuesKeamblesan, local forest loss For buffering, quality etc dumpsite.

System-Underground Mining Systems:Stope with natural buffering:- Open stope with underhand stoping- Open stope with an overhand stoping- Open stope with breast stoping (room and pillar)- Sublevel stoping

Stope with artificial buffering:- Cut and fill stoping- Shringkage stoping- Square-set stoping- Stull stoping- Longwall mining- Undercut and fill- Top sliocing

Caving method:- Sub-level caving- Block caving

Open stope natural:- Deposits with ore and a powerful wall, except that thin that pd ceb flat / slightly sloping Mine where retrievable in the system with backward- Buffer BRP SHG ore ore insolubility taken.- Mining scr selective- Pd flat deposits, ore sorting possible at BWH tnh, For steep dip sorting was done scr limited- Limited pd tabular deposits with regular BTK, DDG clearly limits to likewise biased ttp large deposits, clumping, irregular.

Stope underhand open stopingApplication:- End with a 3-4 m thick- Dip 50 which allows gravity displacement pd bo- Via the method gains menganbil For bjh entirely separate entity dr dr dd mm main or main bag which provide a suitable condition.- Hangingwall and footwall ore competent For reducing the use of pillars.- BJH krn would be ill competent workers mjd beachhead.Advantages:- Performance of well drilling.- Need a little penyanga material- Utilize g to move the broken ore- Drilling downward- Loss of fine bjh high kdr 50 morbidly biased workers stand in the footwall For SHG need to create a platform restsAdvantages:- Heading back ill follow back mining hazards SHG Because the interval level can be> than the open stope underhand stoping- Sorting systematic- Waste easily stacked the mountainous areas of the mine- Safe working conditions, conditions of application elatis- Pd small slope that falls pd Bro ore haulage drive scr gravityDisadvantages:- Performance drilling down- Dip> 45 required patform For stand- Material support many- Loss of high levels bjh uk hls greater

Open Stope Breast stoping (Stop and Pillar):Application:- Deposits morbidly high value that allows a number of ore left as pillars- Thickness 7 m may be mined ttp bjh loss and the greater the roof collapsed- Dip 20-50: horizon n pillar stope mining is applied For deposits that flat / nearly flatinclined: 20 -30, mining the direction of the slope and morbidly step allows the use of mobile mining equipment: 30-50, scr penamabangan sequentially to produce the work area with a slope that allows the use of mobile equipment.- Strong roof and floor rock, to minimize the use of pillars- Ore hrs strung out to reduce the width of the pillar- Depth morbidly too big For reducing the burden that must be supported pillarAdvantages:- Low cost- Allows the selection and stope pd pd waste space left blank- Allow the mechanization dr drilling until loading with used trackless- Rapid development and dev do pd ore itselfDisadvantages:- Lost ore to 40% pd pillar with pillar robbing jk mjd 20%- Danger dr hanggingwall debris, and when the hangingwall mpy joint and crack that allows debris slab parallel to a big bat.- Local ventilation is very broad.

Sublevel stoping:Application:- Dip 50-90 (steeply) is the slope of the fw> drpd slip angle bo- Hanging and fotter hrs competent- Bjh hrs competent- Bjh with uneven levels limit the spread of- Bjh sulfur flotation treatment needAdvantages:- For reducing the delay drilling blasting, scaling, mucking- Pemb continuous scr pd dev.- Longhole driller interchangeable detonated around the stope ore For bro give that much.- Flexible- Safe fire drDisadvantages:- Do the unthinkable scr effective sorting- Large blocks of ore bro can clog grawpoints- Ventilation difficult- A large cavity- Losses and substantial dilution- Which requires a long period prev stope berprod

Stope with Buffer ArtificialCut and fill stoping:Application:- For replacing sublevel stoping and shrinkage stoping mining pd nut mjd rocks within which the voltage is very large.- Coal competent- Hanging and foot may be ill competent considering they will almost scr lanmgsung propped up with filling material- Bjh boundary with regular paddling and bjh who discontinue, mk do pd ore mining high grade and low grade ore left as filling- To take any high grade pillars- Dip higher than shringkage and sublevel stoping- Easy to set up ventilation- A minimum dilution- The wall between two adjacent stope bias which is thinner than the other methods of stoping reply- Stope flexible to the narrow high grade ceb- Because DDG stable stope weak propped filling with wasteDisadvantages:- Need expensive filling material- So much for addressing labor needs filling- It took a lot of water pot for pulp- More expensive than the shrinkage and sublevel stoping- Cement and finely psr For filling bias clogging the pump / pipe- Dr. stope limited output Because the activity of filling

Sublevel advantage thd sringkage:- Risk of fire