RAZVOJ 3D NUMERIČKOGA MODELA ZA SIMULACIJU SUSTAVA ŠIRENJA UDARNOGA VALA S OBZIROM NA POLOŽAJ BUŠOTINE I IN SITU DISKONTINUITETE

Blasting operations are one of the most important parts of geotechnical and mining projects. Most rocks naturally have a series of discontinuities that significantly affect their responses to blast waves. In this paper, the propagation of a blast wave in one intact rock and four rocks with different joint conditions are simulated by a 3-dimensional distinct element code. The results showed that the joint in the model acted as a wave barrier and passed part of the waves, absorbed a portion, and reflected the remaining part into the model. In other words, a discontinuity reduces the energy of the wave and causes more wave attenuation. In addition, a shorter distance between the joint and the hole causes slower wave propagation and greater damping. Moreover, the results showed that the smaller the angle between the discontinuity and axis of the blast holes, the more stress occurs in the rock bench.Proces miniranja jedan je od najvažnijih dijelova geotehničkih i rudarskih projekata. Većina stijena prirodno ima niz diskontinuiteta koji znatno utječu na njihovu postojanost na udarne valove. U ovome radu širenje vala miniranja u jednoj neoštećenoj stijeni i četiri stijene s različitim uvjetima pukotina simulirano je trodimenzionalnom metodom diskretnih elemenata. Rezultati su pokazali da pukotina u modelu djeluje kao valna barijera i propušta dio valova, dio apsorbira, a drugi dio reflektira u model. Drugim riječima, diskontinuitet smanjuje energiju vala i uzrokuje veće slabljenje vala. Osim toga, kraća udaljenost između pukotine i bušotine uzrokuje sporije širenje valova i veće prigušivanje. Štoviše, rezultati su pokazali da što je manji kut između diskontinuiteta i osi bušotina, to se više naprezanja javlja u stijeni

NAČIN PROCJENE I KLASIFIKACIJE KAMENOLOMA OBLIKOVANOGA KAMENA S NAGLASKOM NA SIGURNOSNE PARAMETRE

Building, dimensional and decorative stones from mining and industry are among the significant resources of Iran. Following China and Italy, Iran is in third place of world production, but only has a minor contribution in international trade. One main reason of this problem is negligence regarding the introduction of dependable mines to foreign customers. On the other hand, the frequency of fatal and non-fatal accidents in these mines implies the necessity of more attention to safety parameters. The first stage to attain this aim is identifying the major factors on safety of these mines and ranking the major mines considering these indices. In this paper, a comprehensive model for ranking of mines in the sense of all imposing attributes with an emphasis on safety parameters is presented. In order to validate the model, 19 active mines of the Pyrtak Company in Lorestan province have been used. In this paper, after determining all the parameters of safety in decorative stone mines and weighting these attributes, using AHP-TOPSIS and fuzzy environment, mines have been ranked. After a systematic evaluation of the decorative stone mines, the most appropriate mine is selected.Građevinski, oblikovani i ukrasni kamen te kamenolomi iz kojih se pridobivaju pripadaju važnoj gospodarskoj grani u Iranu. Danas je ta zemlja, nakon Kine i Italije, na trećemu mjestu po pridobivanju takvih sirovina u svijetu. Međutim, u svjetskoj trgovini takvim kamenjem sudjeluje sa znatno manjim udjelom. Jedan je od razloga nedostatak predstavljanja aktivnosti vezanih uz tu gospodarsku granu inozemnim kupcima. Nadalje, broj nesreća, s ozbiljnim i manjim posljedicama, pokazao je kako se njihovu sprječavanju mora posvetiti više pozornosti. Prvi korak u tome je prepoznavanje svih onih faktora koji na to mogu utjecati te rangiranje najvećih kamenoloma po sigurnosnim kriterijima. Stoga je ovdje prikazan opsežan model za rangiranje kamenoloma, u kojemu su izdvojene sve nužne varijable važne za sigurnost rada. U cilju provjere modela analizirano je 19 kamenoloma koje vodi tvrtka Pyrtak u provinciji Lorestan. Nakon određivanja uvjeta u kamenolomima ukrasnoga kamena i određivanja njihova utjecaja primijenjena je metoda AHP-TOPSIS koja se temelji na neizravnoj logici. Kamenolomi su rangirani prema rezultatima te je izdvojen onaj s najprimjerenijim načinom rudarenja

ISTRAŽIVANJE SVEOBUHVATNOGA MODELA ZA PROCJENU OBRADBENOGA I OKOLIŠNOGA RIZIKA KOD VAĐENJA ARHITEKTONSKO-GRAĐEVNOGA KAMENA

One of the most hazardous fields of engineering is mining operations and accordingly, it requires extra consideration on risk evaluation. Decorative stone quarrying is one of the main branches of the mining industry in Iran. Currently, Iran, China and Italy are known as the three main producers of decorative stones in the world. Subsequently, risk assessment is one of the main steps of quarrying organization. One of the main steps of risk assessment is Risk Breakdown Structure (RBS). In order to achieve this goal, a comprehensive structure of dimensional stone quarrying is modelled in this research and divided into 17 main levels. One of the most useful procedures of risk ranking is Multi attribute decision-making methods which state that they have numerous affecting parameters. In the next step of this study, the main hazards of main decorative stone quarrying are assessed by implementing the ‘Preference Ranking Organization Method for Enrichment Evaluation’ (PROMETHEE) technique. As a final point, Economical, Management, and Schedule risks are determined as the most intimidating hazards in this field.Jedna od najopasnijih inženjerskih aktivnosti jesu rudarske operacije koje stoga zahtijevaju dodatne procjene rizika. Vađenje ukrasnoga kamena jedna je od glavnih rudarskih grana u Iranu. Trenutačno su Iran, Kina i Italija tri glavna proizvođača takva kamena u svijetu. Procjena rizika među temeljnim je aktivnostima kamenoloma. Jedan od glavnih postupaka toga procesa jest procjena rizika loma strukture (RLS). S tim ciljem modelirane su makrostrukure arhitektonsko-građevnoga kamena te su podijeljene u 17 razina. Jedan od najboljih postupaka za rangiranje rizika jest višeatributna metoda donošenja odluka koja povezuje brojne zavisne parametre. Nadalje, ocijenjeni su glavni rizici u najvećim kamenolomima uporabom metode preferirajućega rangiranja za poboljšanu procjenu (MPRPP). Na kraju su izračunani ekonomski rizik te rizici upravljanja i planiranja, koji ujedno imaju najveći utjecaj na opisane aktivnosti

INVESTIGATING AN INNOVATIVE MODEL FOR DIMENSIONAL SEDIMENTARY ROCKS CHARACTERIZATION USING ACOUSTIC FREQUENCIES ANALYSIS DURING DRILLING

Određivanje geomehaničkih svojstava stijena ima važnu ulogu u njihovim opisima i karakterizacijama u svim geoznanostima. Samo bušenje takvih stijena gotovo je obvezatna operacija koja se izvodi tijekom njihova ispitivanja i pridobivanja. Pri tome nastaju zvučni (akustični) valovi, kao rezultat uporabe različite opreme za bušenje. Upravo uporaba tih valova može pomoći kod određivanja geomehaničkih svojstava (pro)bušenih stijena. Takav postupak relativno je jeftin, a pruža zadovoljavajuću razlučivost ispitivanja. U radu je prikazan prilino nov pristup povezanoga računa geomehaničkih svojstva taložnih stijena i prevladavajućih zvučnih frekvencija, primjenom brze Fourierove transformacije. Također je razvijena izvorna, eksperimentalna rotacijska oprema za bušenje. Njome je obrađeno deset uzoraka prikupljenih u različitim taložnim bazenima Irana s različitim geomehaničkim svojstvima. Dobiveni su rezultati svojstava samih uzoraka, ali i prostora u kojima su prikupljeni. Zaključeno je kako postoje pouzdane matematičke veze između svojstava različitih taložnih stijena, opisanih varijablama jednoosne tlačne čvrstoće, vlačne čvrstoće, šupljikavosti i tvrdoće, te snimljenih zvučnih (akustičnih) frekvencija.Determining geomechanical characteristics of rocks plays a significant role in all consequent designing stages of geosciences. On the other hand, drilling is one of the considerable operations in primer phases of extracting rocks. Drilling process produces acoustic signals as by-product during drilling. Then, one possible way for predicting geomechanical properties of rocks, is employing acoustic signal frequencies which are produced during drilling operation. This process helps to geoengineers for determining rock characteristics in short time and by low-cost and satisfying precision. This research tries to develop a novel computational relations between geomechanical characteristics of sedimentary rocks and produced dominant acoustic frequencies by implementing Fast Fourier Transform (FFT). For this purpose, a novel rotary drilling machine is developed by researchers. In order to introducing reliable model, 10 diverse sedimentary rock samples from various sedimentary basins of Iran are gathered in wide range of geomechanical features, and all tests are carried out on them. The results of this research could be used for sedimentary basins\u27 characterization. Results show there are reliable mathematical relations between various characteristics of sedimentary rocks (UCS, TS, porosity and hardness) and diverse dominant frequencies

ISTRAŽIVANJE ZVUČNOGA ZAPISA U RAZLIČITIM VRSTAMA STIJENA NA TEMELJU VRIJEDNOSTI RMS ZVUČNOGA SIGNALA

Recent years have seen a vast increase in the use of acoustic waves in real-time and non-destructive detection and monitoring applications in various industries such as mining. Acoustic signal processing methods can provide accurate and reliable estimates of the condition of a process or material in a highly cost-effective way without interrupting the ongoing operations. This paper investigated whether the class of a rock and its strength properties can be estimated based solely on acoustic signals captured during drilling operations. For this purpose, uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), the Schmidt rebound number (SRN), and longitudinal wave velocity (Pw) of a series of samples of sedimentary, metamorphic and igneous rocks were measured in a rock mechanics laboratory. The samples were then subjected to a drilling test and the acoustic signal propagating in the drilling medium was recorded by an acoustic sensor. After obtaining the time spectrum of the captured signals, their RMS values were calculated and compared with the mechanical properties of the corresponding rock samples. For the rocks tested in this study, the obtained RMS values were in the range of 800 to 1,600, and generally increased with an increase in strength and hardness. The RMS values obtained for each class of rocks had their own specific range. For sedimentary rocks, this range was 800 to 1000, for metamorphic rocks, it was 1000 to 1200, and for igneous rocks, it was 1400 to 1600. Given the differences in the range of RMS values obtained from the acoustic signals of drilling, these values can be used in the estimation of rock class and strength properties. These results show that there is significant potential for the future use of this approach in the industry for field identification and classification of rocks, especially in deep drilling operations or when there is little information about the characteristics of the rock being drilled.Proteklih godina ostvaren je velik napredak u uporabi zvučnih valova kao trenutačne i neinvazivne metode opažanja i praćenja različitih operacija u rudarstvu i drugim industrijskim granama. Obradba zvučnih signala može omogućiti točnu i pouzdanu procjenu uvjeta procesa ili materijala na ekonomski vrlo isplativ način te bez prekidanja tekućih radova. Ovdje je prikazano ispitivanje sa svrhom mogućnosti procjene vrste i čvrstoće stijene isključivo uporabom zvučnih valova, a tijekom bušenja. Izmjereno je na nizu uzoraka taložnih, metamorfnih i magmatskih stijena vrijednosti jednoosne tlačne čvrstoće, brazilskoga testa vlačne čvrstoće, Schmidtova odskoka i brzine longitudinalnih valova. Zatim su uzorci podvrgnuti testu bušenja i širenja zvučnih valova u bušenome uzorku koji su i snimani. Dobivena je vremenska raspodjela takvih signala, a izračunane su njihove RMS vrijednosti i uspoređene su s mehaničkim svojstvima odgovarajućih stijenskih uzoraka. Kod stijena obrađenih ovim istraživanjem vrijednost RMS-a kretala se između 800 i 1600, a općenito je rasla s povećanjem čvrstoće i tvrdoće. Vrijednosti RMS-a prikupljene su za svaku klasu stijena u specifičnome intervalu. Kod taložnih on je iznosio 800 – 1000, metamorfnih 1000 – 1200 i magmatskih 1400 – 1600. Razlike u vrijednostima RMS-a dobivene iz zvučnih signala generiranih bušenjem mogu se koristiti za procjenu vrste i čvrstoće stijena. Rezultati pokazuju kako takav pristup ima znatan potencijal za buduću uporabu kod terenskoga prepoznavanja i razvrstavanja stijena, posebno kod dubokih bušenja, a pogotovo u slučajevima kada je takvim bušenjima prikupljeno malo podataka

Feeding di-ammonium phosphate as a phosphorous source in finishing lambs reduced excretion of phosphorus in feces without detrimental effects on animal performance

Objective Phosphorous (P) sources with greater bioavailability might increase animal production efficiency and decrease environmental pollution. The objective of current study was to determine animal performance, nutrient digestibility, blood metabolites and fecal P concentration in finishing lambs fed a diet with either di-calcium phosphate (DCP) or di-ammonium phosphate (DAP) as a P source. Methods Twelve 4-month-old male lambs (initial body weight 24.87±3.4 kg) were randomly allocated to a diet with either DCP or DAP (~261 g/kg of total diet P) fed ad libitum for 93 days. Diets were iso-nitrogenous and iso-energetic and had same calcium (Ca) and P concentrations. Results The DAP contained 19.7 g/kg of dry matter (DM) Ca, 185.4 g/kg DM P and 14,623 ppm fluorine, while DCP contained 230.3 g/kg DM Ca, 195.2 g/kg DM P and 1,039 ppm fluorine. The diet with DAP contained 60 ppm fluorine while the diet with DCP contained 13 ppm fluorine. Lambs fed the diet with DAP tended to have a greater daily DM intake compared to those fed diet with DCP (p = 0.09). Lambs fed DAP had greater plasma P concentration and alkaline phosphatase activity (p≤0.01) compared with lambs fed DCP. Dry matter and organic matter digestibility of the diets were similar between two treatments at days 60 and 90, while they were greater in lambs fed DCP (p<0.05) at day 30 of the trial. Feeding DAP increased P digestibility (58.7% vs 50.2%; p<0.05) and decreased fecal P concentration in lambs compared with feeding DCP (3.1 vs 3.8 g/kg DM; p<0.05). Conclusion Providing ~261 g/kg of total diet P as DAP in the diet of finishing lambs improved the bioavailability of P in the body and decreased excretion of P in feces without affecting lamb performance

OPTIMIZACIJA GALVANSKOGA IZLUŽIVANJA HALKOPIRITA UPORABOM PIRITA I SREBRA KAO KATALIZATORA TE UPORABOM METODE ODZIVNE POVRŠINE

In this research, dissolution of chalcopyrite concentrate is modelled and optimized using Response Surface Methodology (RSM). Also, effective parameters in the leaching process such as the amount of pyrite, silver ions, redox potential and initial concentration of acid are comprehensively studied. Central Composite Design (CCD) methodology is chosen as the design matrix to predict the optimum level of the parameters. In the next step, it will be proven that in the presence of silver ions, pyrite effectiveness is improved and also the chalcopyrite dissolution rate is increased considerably. Using the result of quadratic programming, a rotation speed of 1000 rpm, a pyrite/chalcopyrite mass ratio of 3:1, the amount of 150 ppm silver ion, a solution potential set point of 470 mV, at 800°C and 25 g/L initial acid concentration are the optimal level of the selected parameters wherein the maximum copper extraction with more than 95% in less than 10 hours can be accessible.U ovome istraživanju modelirano je otapanje koncentriranoga halkopirita te je proces optimiziran uporabom metode odzivne površine. Također su istražene efektivne varijable tijekom toga procesa, i to količina pirita, iona srebra, redokspotencijal i početna koncentracija kiseline. Metodom središnjega kompozitnog dizajna određena je matrica za predviđanje najboljega odnosa tih varijabli. Nakon toga je pokazano kako nazočnost iona srebra povećava efi kasnost pirita, što je rezultiralo znatno većom topivošću halkopirita. Kvadratičnim programiranjem određene su sljedeće vrijednosti kao optimalne: brzina rotacije od 1000 okretaja u minuti, zatim maseni odnos pirita i halkopirita 3 : 1, koncentracija iona srebra 150 ppm, potencijal topivosti od 470 mV na 800 ⁰C te početna koncentracija kiselina 25 g/L. Time je postignuto maksimalno izluživanje bakra (uspješnosti veće od 95 %) za vrijeme kraće od 10 sati

THE DEVELOPMENT OF A NOVEL MODEL FOR MINING METHOD SELECTION IN A FUZZY ENVIRONMENT; CASE STUDY: TAZAREH COAL MINE, SEMNAN PROVINCE, IRAN

Odabir rudarske metode za bilo koju mineralnu sirovinu najvažniji je korak kod započinjanja i održavanja uspješnoga rudarenja. S obzirom na velike troškove i utjecaj na okoliš odabranu rudarsku metodu pridobivanja obično je nemoguće promijeniti kada pridobivanje započne. Odabir metode uglavnom se temelji na geološkim i geometrijskim svojstvima sirovine, utjecaju na okoliš, mogućim opasnostima te općenito uporabi tla na kojemu se rudari. U radu je prikazan razvoj nove metode kojom se postiže stabilan iznos proizvodnje, ali i smanjuju problemi u okolišu. Njezina uporaba objašnjena je na primjeru rudnika ugljena Tazareh. Istaknuti su nedostatci prethodnih rudarskih metoda te kako su oni riješeni novim pristupom nazvanim TOPSIS. Rije« je o postupku odlučivanja s više varijabli, oblikovanome neizrazitom logikom. Danas je upravo ta metoda u primjeni u navedenome rudniku.Mining method selection (MMS) for mineral resources is one of the most significant steps in mining production management. Due to high costs involved and environmental problems, it is usually not possible to change the coal mining method after planning and starting the operation. In most cases, MMS can be considered as an irreversible process. Selecting a method for mining mainly depends on geological, geometrical properties of the resource, environmental impacts of exploration, impacts of hazardous activities and land use management. This paper seeks to develop a novel model for mining method selection in order to achieve a stable production rate and to reduce environmental problems. This novel model is illustrated by implementing for Tazareh coal mine. Given the disadvantages of the previous models for selecting coal mining method, the purpose of this research is modifying the previous models and offering a comprehensive model. In this respect, TOPSIS method is used as a powerful multi attribute decision-making procedure in Fuzzy environment. After implementation of the presented model in Tazareh coal mine, long wall mining method has been selected as the most appropriate mining method

Morphological Characteristic, Chemical Composition and In Vitro Gas Production Fermentation Profiles of Alfalfa Hay at Early Bud Stage Harvested at Different Cuts and in the Afternoon and in the Morning

There are a little information about nutritive value of alfalfa harvested at different cuts and different cutting time (morning and afternoon) in semiarid climate condition of north east of Iran. Effects of different harvesting cuts and cutting time (6 A.M and 6 P.M) of alfalfa hay at early bud stage on chemical composition and in vitro gas production fermentation profiles were studied in this experiment. Alfalfa hay that harvested at spring cuts had more CP and Ash content, gas production, ME, NEl, SCFA (short chain fatty acid), and IVOMD (In vitro organic matter digestibility) and less NDF and ADF than summer cuts. Alfalfa that cuts in the morning had more CP content and less leaf content and leaf to stem ratio than alfalfa cuts in the afternoon. Cutting alfalfa in the morning and the afternoon had no effect on fermentation profiles of alfalfa hay. The results of this experiment show that alfalfa hay at early bud stage harvested in spring and in the afternoon had more nutritive value than alfalfa harvested in summer and in the morning

Carbohydrate and lipid spectroscopic molecular structures of different alfalfa hay and their relationship with nutrient availability in ruminants

Objective This study was conducted to determine molecular structures related to carbohydrates and lipid in alfalfa hay cut at early bud, late bud and early flower and in the afternoon and next morning using Fourier transform infrared spectroscopy (FT/IR) and to determine their relationship with alfalfa hay nutrient profile and availability in ruminants. Methods Chemical composition analysis, carbohydrate fractionation, in situ ruminal degradability, and DVE/OEB model were used to measure nutrient profile and availability of alfalfa hay. Univariate analysis, hierarchical cluster analysis (CLA) and principal components analysis (PCA) were conducted to identify FT/IR spectra differences. Results The FT/IR non-structural carbohydrate (NSCHO) to total carbohydrates and NSCHO to structural carbohydrate ratios decreased (p<0.05), while lignin to NSCHO and lipid CH3 symmetric to CH2 symmetric ratios increased with advancing maturity (p<0.05). The FT/IR spectra related to structural carbohydrates, lignin and lipids were distinguished for alfalfa hay at three maturities by PCA and CLA, while FT/IR molecular structures related to carbohydrates and lipids were similar between alfalfa hay cut in the morning and afternoon when analyzed by PCA and CLA analysis. Positive correlations were found for FT/IR NSCHO to total carbohydrate and NSCHO to structural carbohydrate ratios with non-fiber carbohydrate (by wet chemistry), ruminal fast and intermediately degradable carbohydrate fractions and total ruminal degradability of carbohydrates and predicted intestinal nutrient availability in dairy cows (r≥0.60; p<0.05) whereas FT/IR lignin to NSCHO and CH3 to CH2 symmetric stretching ratio had negative correlation with predicted ruminal and intestinal nutrient availability of alfalfa hay in dairy cows (r≥−0.60; p<0.05). Conclusion FT/IR carbohydrate and lipid molecular structures in alfalfa hay changed with advancing maturity from early bud to early flower, but not during the day, and these molecular structures correlated with predicted nutrient supply of alfalfa hay in ruminants