14 research outputs found
UTJECAJ TVRDOÄE STIJENE NA USITNJAVANJE HIDRAULIÄNIM ÄEKIÄEM I NA DROBLJENJE U ÄELJUSNOJ DROBILICI
The physical and mechanical characteristics of intact rocks depend on the way of their formation, sustained deformations and the process of wearing a specific rock has been exposed to. These characteristics have a rather high influence on the technological process of extraction and dressing of mineral raw materials. However, the mechanical characteristics of rocks due to use of explosives for their extraction in the open pit have a more significant impact. The rock blocks extracted by blasting which are larger than the opening of the primary crusher are usually fragmented by hydraulic hammer. The paper presents the results of the testing of impact of rock hardness on fragmentation of rocks by means of hydraulic hammer and during crushing in jaw crusher. The testing was carried out on the rock samples from five quarries. According to the obtained results the hardness has a considerably larger impact on the fragmentation energy by hydraulic hammer than on the crushing energy in jaw crusher.FiziÄko-mehaniÄke znaÄajke intaktne stijene ovise o naÄinu postanka, pretrpjelim deformacijama i procesu troÅ”enja kojima je pojedina stijena bila izložena. Ove znaÄajke imaju velik utjecaj na tehnoloÅ”ki proces dobivanja i oplemenjivanja mineralnih sirovina. MeÄutim, puno veÄi utjecaj imaju izmjenjena fiziÄko-mehaniÄka svojstva stijena uslijed upotrebe eksploziva za njihovo otkopavanje pri povrÅ”inskoj eksploataciji. Blokovi stijena dobiveni miniranjem koji su veÄi od ulaznog otvora primarne drobilice obiÄno se usitnjavaju hidrauliÄnim ÄekiÄem. U radu su prikazani rezultati ispitivanja utjecaja tvrdoÄe stijena na usitnjavanje stijena hidrauliÄnim ÄekiÄem i tijekom drobljenja u Äeljusnoj drobilici. Ispitivanje je provedeno na uzorcima stijena iz pet kamenoloma. Rezultati su pokazali da tvrdoÄa ima znatno veÄi utjecaj na energiju usitnjavanja hidrauliÄnim ÄekiÄem nego na energiju za drobljenje u Äeljusnoj drobilici
CONSTRUCTION AND TESTING OF THE MEASUREMENT SYSTEM FOR EXCAVATOR PRODUCTIVITY
HidrauliÄni bager jedan je od najÄeÅ”Äe koriÅ”tenih strojeva u rudarstvu, graditeljstvu i geotehnici. Kao takav korisnicima predstavlja i važnu stavku u troÅ”kovima goriva i održavanja. Detaljna mjerenja uÄinka ovoga stroja izvode se u svrhu poboljÅ”anja efikasnosti odnosno uÅ”tede. Mjerni sustav s takvom svrhom može biti složen i skup, tražiti specijalnu opremu proizvoÄaÄa stroja te ne postoji kao gotovo rjeÅ”enje koje bi omoguÄavalo praÄenje radnih parametara poput trajektorije lopate, sila i energije kopanja, visine radnoga Äela i sl.
Iz toga razloga osmiÅ”ljen je i testiran sustav za praÄenje radnih parametara i uÄinka bagera. Sustav se sastoji od triju pretvornika linearnoga pomaka i triju pretvornika tlaka, za mjerenje produljenja i tlakova hidrauliÄnih cilindara, te jednoga žiroskopa za mjerenje kuta zakretanja bagera. Pretvornici su spojeni na jedinicu za prikupljanje podataka, opremljenu SD karticom i 12-bitnim AD pretvaraÄem. Jedinica je bazirana na Atmega328 mikrokontroleru, Å”to omoguÄava primjenu Arduino suÄelja za programiranje i razvijenih biblioteka koda.
Mjerni sustav testiran je laboratorijski radi odreÄivanja toÄnosti, rezolucije i moguÄe brzine uzorkovanja podataka. Tlakovi mogu biti mjereni u rasponu 0 bar ā 500 bar s toÄnoÅ”Äu od 0,026 % MO i rezolucijom 0,15 bar. IzvlaÄenje cilindra može biti mjereno u rasponu 0 mm ā 2300 mm, s toÄnoÅ”Äu od 0,087 % MO i rezolucijom 0,58 mm. ToÄnost mjerenja kuta zakretanja iznosi 1,2Ā° po okretu ili 0,33 % MO. Testirana brzina uzorkovanja iznosi 39 Hz ā 588 Hz, ovisno o programskome kodu.hydraulic excavator is one of the most used machines in mining, construction and geotechnics. Monitoring its productivity can provide benefits such as savings in fuel consumption and maintenance, cost optimization of working parameters and a higher working efficiency. A measurement system for such a purpose can be complex and expensive, as it requires special equipment from the manufacturer and does not exist as an out of the box solution that would measure working parameters such as bucket trajectory, digging energy, digging force, etc.
A measuring system was designed to monitor productivity and gather working parameters. It consists of three pressure transmitters for measuring cylinder pressures, three draw wire sensors for cylinder elongations, one inertial measurement unit for the measurement of swing angle and one logger unit for data acquisition and storage. The logger unit, equipped with an SD card module and 12-bit AD converter, is based on Atmega328 microcontroller, which allows for the usage of Arduino IDE and already developed libraries.
The system was tested in a laboratory to determine its accuracy, resolution and usable sample rate. Cylinder pressure can be measured in the range of 0-500 bar with an excellent accuracy of 0.026 % FSO and 0.15 bar resolution. Cylinder elongation can be measured in the range 0-2300 mm with an accuracy of 0.087 % FSO and 0.58 mm resolution. Swing angle measurement accuracy is 1.2Ā° per circle or 0.33 % FSO. The usable sample rate of the system is found to be 39 Hz-588 Hz, depending on the logger executing code
DEPENDENCY OF SPECIFIC ENERGY OF ROCK CUTTING ON SPECIFIC DRILLING ENERGY
SpecifiÄna energija veliÄina je koja povezuje radne veliÄine stroja sa znaÄajkama stijene u kojoj stroj radi, a jednaka je ukupnome radu potrebnom za razruÅ”avanje jediniÄnoga volumena stijene. Pretpostavlja se da kod strojeva koji imaju istu ili sliÄnu mehaniku razruÅ”avanja stijena, a koji se koriste za razliÄite namjene (npr. rezanje i buÅ”enje stijena), po stoji znatna zavisnost izmeÄu specifiÄnih energija. Prilikom eksploatacije arhitektonsko-graÄevnoga kamena Äesto se koristi lanÄana sjekaÄica i rotacijska buÅ”ilica, tj. strojevi koji služe za rezanje, odnosno buÅ”enje stijene, a Äija je mehanika razruÅ”avanja vrlo sliÄna. Radi odreÄivanja zavisnosti specifiÄne energije rezanja stijena o specifiÄnoj energiji buÅ”enja provedena su preliminarna laboratorijska ispitivanja na ureÄaju za pravolinijsko rezanje stijena i laboratorijskoj buÅ”ilici kojima je simulirano rezanje stijena lanÄanom sjekaÄicom, tj. buÅ”enje stijena rotacijskim buÅ”enjem. Analizom mjernih rezultata dobivene su smjernice za nastavak laboratorijskih ispitivanja odnosno provedbu terenskih ispitivanja.Specific energy is the measure which connects the operating parameters of the machine with the characteristics of the rock in which the machine works and is equal to the total work required to break a unit volume of the rock. It is assumed that in machines with the same or similar rock breaking mechanics used for different purposes (e.g. cutting and drilling of rocks), there is a significant dependence on their specific energy values. In the exploitation of dimension stone a chain saw and a rotary drill are often used, i.e. the machines for rock cutting or rock drilling whereas their mechanics of rock breaking is very similar. In order to determine dependence of the specific energy of rock cutting on the specific drilling energy, preliminary laboratory tests were carried out on a linear cutting machine and a laboratory drill with simulated cutting of rocks with a chain saw, and drilling by rotary drilling. The analysis of the measurement results has provided the guidelines for the continuation of laboratory testing, i.e. field testing
IMPACT OF ROCK HARDNESS ON FRAGMENTATION BY HYDRAULIC HAMMER AND CRUSHING IN JAW CRUSHER
The physical and mechanical characteristics of intact rocks depend on the way of their formation, sustained deformations and the process of wearing a specific rock has been exposed to. These characteristics have a rather high influence on the technological process of extraction and dressing of mineral raw materials. However, the mechanical characteristics of rocks due to use of explosives for their extraction in the open pit have a more significant impact. The rock blocks extracted by blasting which are larger than the opening of the primary crusher are usually fragmented by hydraulic hammer. The paper presents the results of the testing of impact of rock hardness on fragmentation of rocks by means of hydraulic hammer and during crushing in jaw crusher. The testing was carried out on the rock samples from five quarries. According to the obtained results the hardness has a considerably larger impact on the fragmentation energy by hydraulic hammer than on the crushing energy in jaw crusher
Research on Interdependence between Specific Rock Cutting Energy and Specific Drilling Energy
A method based on extensive laboratory and field measurements was developed to determine the dependence of specific rock cutting energy (SEc) on specific drilling energy (SEd) for machines with different operating and design characteristics and similar breaking mechanics. Laboratory measurements were performed on a linear rock cutting device and a laboratory drill, using a measurement system to measure electrical power and cutting forces using force/torque transducers. Field power consumption measurements were performed on a chainsaw cutting machine and a hydraulic rotary drill under real working conditions in the dimension stone quarries. The analysis of the measured results confirmed the strong dependence of the specific rock cutting energy on the specific drilling energy and confirmed that laboratory devices can be used to simulate actual rock cutting and drilling process. In addition, the results are applicable in the dimension stone exploration and exploitation phase in order to assess and reduce energy consumption by optimizing the operating parameters of the chain cutter and/or the hydraulic rotary drill
DEPENDENCY OF SPECIFIC ENERGY OF ROCK CUTTING ON SPECIFIC DRILLING ENERGY
Specific energy is the measure which connects the operating parameters of the machine with the characteristics of the rock in which the machine works and is equal to the total work required to break a unit volume of the rock. It is assumed that in machines with the same or similar rock breaking mechanics used for different purposes (e.g. cutting and drilling of rocks), there is a significant dependence on their specific energy values. In the exploitation of dimension stone a chain saw and a rotary drill are often used, i.e. the machines for rock cutting or rock drilling whereas their mechanics of rock breaking is very similar. In order to determine dependence of the specific energy of rock cutting on the specific drilling energy, preliminary laboratory tests were carried out on a linear cutting machine and a laboratory drill with simulated cutting of rocks with a chain saw, and drilling by rotary drilling. The analysis of the measurement results has provided the guidelines for the continuation of laboratory testing, i.e. field testing
Development of a Reference Device for the Calibration of Optical One-Shot Time-Interval Measurements
This paper presents the development of a device that creates two or more light pulses with a precision time delay in a range from microseconds to several seconds and for the purpose of the calibration of velocity of detonation (VOD) measurement instruments. The device was assembled, programmed, and tested for functionality. Measurements were conducted using a reference counter. First, a precision OCXO (oven-controlled crystal oscillator) was used as a clock source. For verification of programmed subroutines, a counter oscillator output port was used as a source of clock signal for the microcontroller. This enabled the cancellation of possible oscillator errors. The signal had to be converted from an AC sine signal to a signal with positive values only using a clamper circuit. By the proposed solution, a calculable standard of time delay between two light pulses was achieved. According to the obtained results, this device can be used to calibrate field measurement devices for VOD measurements in explosives or some other use where the measurement device records the time interval between multiple light pulses. This enables more confidence in measurement results, faster recognition of instrument drift and increases the quality of measurement
Detecting atypical values and their influence on blast-induced seismic measurement results
Blasting is an essential part of any mining or civil engineering project along with all the benefits that it brings, such as cost and time effectiveness, and safety. Still, there are a few downsides to blasting. Ground oscillation velocity as the most significant impact of blasting has been studied broadly. However, not all measured values should be used for PPV (peak particle velocity) predictor or model development. If a false measured value is included in the model or predictor development, it will provide erroneous results that can lead to the damage of the surrounding structures or an increase in the cost of blasting works. There is no clearly defined procedure for separating atypical values (outliers) within blast-induced seismic-effects measurement data. This paper recommends how to properly validate vibration velocity data by detecting and excluding atypical values and how it influences blast-induced seismic measurement results
Detecting atypical values and their influence on blast-induced seismic measurement results
Blasting is an essential part of any mining or civil engineering project along with all the benefits that it brings, such as cost and time effectiveness, and safety. Still, there are a few downsides to blasting. Ground oscillation velocity as the most significant impact of blasting has been studied broadly. However, not all measured values should be used for PPV (peak particle velocity) predictor or model development. If a false measured value is included in the model or predictor development, it will provide erroneous results that can lead to the damage of the surrounding structures or an increase in the cost of blasting works. There is no clearly defined procedure for separating atypical values (outliers) within blast-induced seismic-effects measurement data. This paper recommends how to properly validate vibration velocity data by detecting and excluding atypical values and how it influences blast-induced seismic measurement results