Drill process monitoring in percussive drilling for location of structural features, lithological boundaries and rock properties, and for drill productivity evaluation

This thesis deals with the application of percussive drill monitoring in the mining and underground construction industries. The technique has been used to provide information on different ground properties and conditions and for drill productivity evaluation. Five different test sites have been used: the OSCAR area in the Kiirunavaara magnetite mine in Kiruna, the Viscaria copper mine in Kiruna, the Zinkgruvan mine in south-central Sweden, the Glödberget tunneling site in Västerbotten county and the Hallandsåsen tunneling site in southern Sweden. A methodology has been suggested and tested for treatment of raw data in order to extract rock dependent parameter variations from variations generated by the drill system itself and other external influences. Prediction of rock hardness and fracturing can be done without initial calibration, providing a good foundation for interpretation by site personnel. The mining applications show that drill monitoring has a very high potential for ore boundary delineation and also for classification of existing rock types. In tunneling applications drill monitoring demonstrates a good capability of foreseeing rock conditions ahead of the tunnel face. Other benefits are the speed of the method, its practicality and the fact that it requires no additional equipment, time or access to the production front. The potential for detailed drill productivity evaluation by drill monitoring has been demonstrated. Detailed information of the time consumption for each activity in the drilling cycle can be presented as well as the distribution of the total production. With this information in hand an indication can be given as to how the overall drilling capacity can be increased. The impact on production of automation, new developments and organization can also be predicted with high accuracy.Godkänd; 1997; 20061128 (haneit

Drill process monitoring in percussive drilling : a multivariate approach to data analysis

Godkänd; 1990; 20080410 (ysko)</p

Face to Surface –Task 1 : Baseline Mapping of the Mining Operation in Aitik

“Face to Surface” is a project within the strategic innovation program “Mining and Metals”, which is a collaboration between Vinnova, Formas and Energy Agency of Sweden with additional funding from Boliden Mineral AB and LKAB. The project is aimed to improve productivity and efficiency of mining activities through optimization of the overall production chain. The current status report corresponds to the first task of the project–Baseline Mapping.The report presents the overall process chain of mining operation in Boliden Aitik copper mine, Sweden. The production chain is initially described as a system of singular processes. Each process is then described in more details, including inter-relations and downstream effects of each process within the operation. The report provides a basis for identification of potential fields of improvement in the process. The subsequent tasks of the project will be conducted upon internal discussions based on the findings of this report.Godkänd; 2015; 20150626 (andbra

TPM framework for underground mobile mining equipment : a case study

In underground mines, mobile mining equipment is critical to the production system. Drill rigs for development and production, vehicles for charging holes, LHDs for loading and transportation, scaling rigs and rigs for reinforcement and cable bolting are all important units in the process to generate a continuous ore flow. For today’s mining companies, high equipment availability is essential to reduce operational and capital costs and to maintain high production. High and controllable reliability is also important especially in attempts to automate the production equipment. This paper compares existing maintenance work in a Swedish and a Tanzanian mine. The various maintenance procedures are identified and evaluated based on a TPM framework.Godkänd; 2011; 20111122 (anngus)</p

Dumping oversize rock fragments in orepasses: the impact on the production cycle of a sublevel caving operation

Oversize rock fragments are highly undesired in a sublevel caving (SLC) operation as they affectthe production cycle, equipment, and infrastructure. In this study, afield test was carried out inMalmberget mine to analyse the impact of oversize fragments on the production cycle and thecosts of different procedures for handling such fragments. The tests involved monitoring ofdumping oversize fragments in two orepasses, one with a grizzly and the other one withouta grizzly, using cameras. The cycle times of load-haul-dump (LHD) machines weredetermined for both orepasses. The results indicate that the grizzly increased the availabilityand productivity of the orepass despite increasing the cycle time of the LHD machines.Moreover, installation of a boulder breaker system along with the grizzly can furtherincrease the productivity and the cost of such a system will be paid offin a shorter time interms of enhanced productivity.Face-to-Surface I

Face to Surface : a fragmentation study

As ore grades have decreased and the mining depth has increased over the past few decades, other characteristics than ore grade and tonnage are becoming important. The underground mining process, from in-situ rock mass characteristics to the final mill product with fully liberated minerals, consists of a chain of unit operations that impact, and are influenced by, fragmentation. This report presents the baseline mapping of the project “From Face to Surface”, studying the effects of fragmentation on the process flow in an underground SLC mine. It analyses the underground unit operations in detail, from mine planning to shafts, and maps the blast fragmentation’s effect on the process flow. The goal is to provide a deeper understanding of fragmentation´s effect on different unit operations. The objective is to describe the mining operation at Luossavaara-Kiirunavaara AB (LKAB) and identify key areas for improving fragmentation. To understand how fragmentation influences different operations in the mine, the project conducted a literature study, collected data and interviewed mine personnel in LKAB’s Malmberget mine. Data were collected from the mine’s internal systems, such as GIRON, WOLIS, IP21 and a local drilling data system. The interviews were conducted in cooperation with research personnel from the mine.This baseline mapping shows that the mining operation in Malmberget is affected by fragmentation in several ways. For some unit operations, the fragmentation has a large impact, while for others, it has none at all. The influence of fragmentation starts with the loading operation after the initial blasting and ends with the crushing operation. For the former, boulders are the largest problem, as they cause a great deal of idle time, either when they have to be moved to a separate drift for secondary blasting or when they create hang-ups in the ore passes. When boulders are dumped into the ore passes, they risk damaging the ore pass walls. If boulders create a hang-up, it has to be removed. If the hang-up must be removed with explosives, there is a risk of further damaging the ore pass. In addition, the toxic fumes created by the explosives hinder production until the pass is ventilated. Finally, hang-ups affect the transportation operation as the trucks cannot use an ore pass blocked by a hang-up or closed for ventilation of toxic fumes. There is also a slight possibility that a boulder which does not get stuck in the ore pass will get stuck on a truck. The last operation affected by fragmentation is crushing; boulders and large fragments risk creating a hang-up in the crusher. There are no reports of problems related to fragmentation after this point.The results suggest that further work and mine trials are required in the following areas: drilling, loading, ore passes and crushers.Godkänd; 2016; 20160607 (anngus

Overall factory average spectrum : global vibration index for diagnosis and prognosis of large sets of rotating machinerry

Godkänd; 2011; 20111129 (parkum)</p

Draw Control Strategy and Resource Efficiency in Sublevel Caving : State-Of-the-Art

Sublevel caving is an underground mass mining method used for extracting different types of ores from the earth crust. Mines using sublevel caving (SLC) as the primary mining method are generally highly mechanized with standardized and independent unit operations. Mine development for caving operations are similar to other underground mining methods, however, the scale of production drilling and blasting performed in caving operations including SLC are larger than many other underground mining methods (such as room and pillar or cut and fill). Loading of the material from the production face in sublevel caving is facilitated by the flow of material under gravity into the production face. A large amount of material is loaded from a limited opening termed as the draw point. Different unit operations (drilling, blasting, loading and transportation) are performed in isolation with each other which leads to standardized procedures and safe operation. The mine design allows for operational agility with respect to ore geometry and inclination. These features give SLC an advantage over other mining methods. However, SLC demands a caving conducive geology along with a large ore footprint. The mining method also registers higher percentage of dilution and ore loss compared to non-caving mining methods. Material flow in SLC has been studied extensively in the past five decades and different methods have been used to simulate material flow in caving operations. Physical models of different scales has been designed for simulating material flow by using sand, gravel or rocks and studying the movement of material inside the model. Initial physical models showed an ellipsoidal zone above the draw point from which material flowed into the draw point. However, subsequent modelling results disagreed with this notion of material flow. Numerical modelling techniques have also been applied to simulate material flow. The models were calibrated against mine or mill production data for optimization. Currently, marker trials are being used to understand material flow in SLC. Markers (numbered steel rods, RFID enabled markers) are installed in boreholes drilled inside the burden of a production ring and based on the recovery sequence of markers, material flow is predicted. Results from physical models, numerical models and marker trials along with mine experience have been used in the past to design draw control strategy for SLC operation. Initial draw control techniques were based on the assumption of uniform flow of material. But with the advancement in modelling techniques, draw control strategies have also changed. Ore flow simulation techniques developed to simulate material flow are being applied to predict the ore grade at draw point and hence help in draw control during the loading process. Recent draw control strategies in some mines have evolved to include production data and metal prices to optimize the loading process in SLC. Monitoring of the ore grade at the draw point is crucial in controlling dilution and increasing ore recovery. Present draw point monitoring technique predicts ore grade by exploiting the differences between ore and waste. The difference between ore and waste can be detected through visual observations, assay sampling or weight measurements. Draw point monitoring gives data for both regulation and calibration of draw control strategies, and provides important information regarding dilution and ore recovery during the loading process. Understanding material flow is vital for improving different aspects of SLC operation but draw control for SLC is an operational activity which regulates the loading process for a given mine design and material flow conditions. Therefore, an effective draw control requires a constant monitoring system and a constant calibration of the loading criteria’s through draw point monitoring for reducing dilution and improving ore recovery.För godkännande; 2016; 20160829 (gurshe)</p

Face to Surface –Task 1 : Baseline Mapping of the Mining Operation in Aitik

“Face to Surface” is a project within the strategic innovation program “Mining and Metals”, which is a collaboration between Vinnova, Formas and Energy Agency of Sweden with additional funding from Boliden Mineral AB and LKAB. The project is aimed to improve productivity and efficiency of mining activities through optimization of the overall production chain. The current status report corresponds to the first task of the project–Baseline Mapping.The report presents the overall process chain of mining operation in Boliden Aitik copper mine, Sweden. The production chain is initially described as a system of singular processes. Each process is then described in more details, including inter-relations and downstream effects of each process within the operation. The report provides a basis for identification of potential fields of improvement in the process. The subsequent tasks of the project will be conducted upon internal discussions based on the findings of this report.Godkänd; 2015; 20150626 (andbra

The use of specific energy in rotary drilling : the effect of operational parameters

In rotary drilling, specific energy is considered to be an important parameter for defining mechanical efficiency of the rock destruction process. Specific Energy is defined as the energy required to remove one unit of rock. Specific energy is the function of the size of the borehole and various operational parameters including feed force, rotation speed, rotation torque and penetration rate. The harder the material, the higher the specific energy. The traditional method to calculate the specific energy is based on the parameters penetration rate, feed force, torque and rotation speed, that can be provided by Measurement While Drilling (MWD) data from the drill process. In this study, MWD data from an open pit mine in Sweden are used to evaluate data trends among logged parameters and calculated average specific energy. The results show that there is a significant hole length dependency for penetration rate and feed force that affects the predicted specific energy. This may be explained by that the hole cleaning efficiency is reduced with increasing hole length. The analysis shows that the specific energy is over-estimated by 45% in the bottom of an 18 m hole compared to the collaring point. The suggested solution is to use hole average or complement the specific energy calculation with a hole length related component.Keywords: Specific energy, Measurement While Drilling (MWD), Rotary drilling, Geo-mechanical response, Rock-destruction processGodkänd; 2015; 20150107 (rajgho