Experimental and Statistical Evaluation of Cutting Methods in Relation to Specific Energy and Rock Properties

In a processing plant, natural stone can be cut by methods such as circular sawing (CS), frame sawing (FS), water jet cutting (WJC) and abrasive water jet cutting (AWJC). The efficiency of cutting systems can be compared using various parameters. In this study, the specific energy values were determined and compared to evaluate the efficiency of rock-cutting methods. Rock-cutting experiments were performed on 12 different types of rock samples using a circular sawing machine and an AWJC machine. The experimental results showed that the specific energy values in AWJC were generally higher than in CS. In addition, the relationships between specific energy values and rock properties were explained in this study. The Shore hardness and abrasion resistance were found to be strongly related to the specific energy values, and according to these parameters prediction charts of specific energy values were created.     

Abrasivity Assessment of Granitic Building Stones in Relation to Diamond Tool Wear Rate Using Mineralogy-Based Rock Hardness Indexes

The objective of the present study was to determine the abrasive wear potential of granites in circular sawing using some mineralogy-based rock hardness indexes. A literature study indicated that little or no attention has been given to assessing this kind of relationship in the field of stone processing. To accomplish this objective, sawing experiments were performed on nine different granites used widely as building and decorative stone materials. The measured sawblade-specific wear rates were correlated with three different rock hardness indexes attained by combining the percentage content of hard mineral constituents with their known hardness values. Statistical analysis of the experimental data revealed that rock hardness indexes that are based on both Vickers hardness number and Rosiwal hardness could be accepted as reliable indicators of granite abrasivity. These two indexes were also found to correlate well with the average power drawn during the process. However, the rock abrasivity index based on Mohs relative scratch hardness did not show statistically significant correlations with sawblade wear rate and power drawn. Although quartz percentage content is regarded as an important abrasivity parameter by practitioners, the observations made here indicate that consideration of quartz percentage content alone is not sufficient to describe the abrasive potential of granites, and thus incorporation of other hard mineral constituents could be more suitable.     

Predicting the Performance of Chain Saw Machines Based on Shore Scleroscope Hardness

Shore hardness has been used to estimate several physical and mechanical properties of rocks over the last few decades. However, the number of researches correlating Shore hardness with rock cutting performance is quite limited. Also, rather limited researches have been carried out on predicting the performance of chain saw machines. This study differs from the previous investigations in the way that Shore hardness values (SH₁, SH₂, and deformation coefficient) are used to determine the field performance of chain saw machines. The measured Shore hardness values are correlated with the physical and mechanical properties of natural stone samples, cutting parameters (normal force, cutting force, and specific energy) obtained from linear cutting tests in unrelieved cutting mode, and areal net cutting rate of chain saw machines. Two empirical models developed previously are improved for the prediction of the areal net cutting rate of chain saw machines. The first model is based on a revised chain saw penetration index, which uses SH₁, machine weight, and useful arm cutting depth as predictors. The second model is based on the power consumed for only cutting the stone, arm thickness, and specific energy as a function of the deformation coefficient. While cutting force has a strong relationship with Shore hardness values, the normal force has a weak or moderate correlation. Uniaxial compressive strength, Cerchar abrasivity index, and density can also be predicted by Shore hardness values.     

Performance Prediction of Large-Diameter Circular Saws Based on Surface Hardness Tests for Mugla (Turkey) Marbles

Surface hardness tests such as Shore hardness (SH) and Schmidt hammer rebound hardness (SR) may provide a quick and inexpensive measure of rock hardness, which may be widely used for estimating the mechanical properties of rock material such as strength, sawability, drillability and cuttability. In the marble industry, circular sawing with diamond sawblades constitutes a major cost in the processing. Therefore, several models based on the relations between hourly slab production (P _hs), rock surface hardness (SH and SR) and mineral grain size (S _cr) were developed using the data obtained from field and laboratory measurements on five different marbles quarried in the Mugla Province of Turkey. The models which include surface hardness and crystal size may as well be used for the prediction of sawability (hourly slab production) of carbonate rocks using large-diameter circular saws.     

Correlation of production rate of ornamental stone with rock brittleness indexes

The prediction of production rate in ornamental stones sawing is very important in cost estimation and process planning of the rock sawing plants. The main aim of this paper is finding a mathematical correlation between production rate and rock brittleness indexes. The utilized data have been collected from several stone factories in Iran. Seventeen different granite and carbonate rocks have been experienced sawing conditions with large-diameter circular saws. The laboratory tests such as uniaxial compressive strength and tensile strength, were carried out on the rock samples which were collected from these factories. The ratio of compressive strength to tensile strength (B ₁), the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength (B ₂), and the area under the line of compressive strength and the line of tensile strength (B ₃) were used as brittleness indexes in this study. Then, the relationships between these brittleness indexes and production rate were investigated by using a regression analysis. The results show that, there is not a good relationship between the production rate and B ₁ and B ₂. However, the production rate correlates with B ₃ very well. Therefore, there is a reliable prediction for ornamental stones production based on B ₃ as a brittleness indexes.     

Prediction of the sawing quality of Marmarit stones using the capability of artificial neural network

The sawing rate is one of the most significant and effective parameters in extracting building stones via diamond wire sawing. This parameter designates the capability of diamond wire sawing for sawing different stones; in addition, the parameter gives rise to economical considerations for quarry designers. In this study, the existent relations between stone geotechnical parameters and the sawing rate of stones via diamond wire sawing were analyzed using regression and correlation coefficient as well as the collected data from Marmarit stone quarries. Moreover, we estimated the sawing rate of Marmarit using the dimensional stone rock mass rating (DSRMR); upon comparison of the data obtained from DSRMR our pre‐collected data on quarries, we did not gain satisfactory results from DSRMR, hence we used artificial neural network (ANN). The results showed that the percentage of Silica, the coefficient of water absorption, the uniaxial compressive strength (UCS), and abrasive hardness are the proper parameters for creating the ANN. Discontinuities have the least effects possible on diamond wire sawing. Having given the training possibility of the ANN, and its ability to evaluate relations among input parameters, the ANN, which was being trained with Marmarit's traits, was an accurate network for estimating diamond wire sawing in Marmarit quarries, although it could not generalize this network for other stones such as Chini and Crystal. Copyright © 2011 John Wiley & Sons, Ltd.     

Recycling waste from natural stone processing plants to stabilise clayey soil

For the countries with a developed stone industry the waste generated in the natural stone processing plants pose environmental and economic problems. The utilisation of stone waste in various areas is still under research. In addition, there are only a limited number of studies concerning the use of stone waste obtained from processing plants in the stabilisation of clayey soil. Furthermore, none of the studies in the literature investigated the effect of the characteristics of the stone on the stabilisation of the soil. This is the first study that compares the efficiency of the waste calcitic marble, dolomitic marble and granite powder as additives for the stabilisation of clayey soil. Artificial soil samples were prepared in the laboratory using bentonite and kaolinite. Natural stone waste powder was added to the soil samples at different percentages, and the index and compaction parameters of the stabilised soil were analysed. The results showed that the types of waste powder used in this study, like lime, could be used as stabilisers. As the percentage of additives increased, the plasticity index of the clayey soil decreased and the physical properties of the soil changed from clay to silt. In terms of compaction parameters, the use of all types of natural waste powder in the study resulted in a decrease in the optimum water content and an increase in the maximum dry unit weight. The lowest optimum water content and the highest maximum dry unit weight were obtained from the dolomitic marble powder.     

The Effects of Operational Parameters on a Mono-wire Cutting System: Efficiency in Marble Processing

Mono-wire block cutting machines that cut with a diamond wire can be used for squaring natural stone blocks and the slab-cutting process. The efficient use of these machines reduces operating costs by ensuring less diamond wire wear and longer wire life at high speeds. The high investment costs of these machines will lead to their efficient use and reduce production costs by increasing plant efficiency. Therefore, there is a need to investigate the cutting performance parameters of mono-wire cutting machines in terms of rock properties and operating parameters. This study aims to investigate the effects of the wire rotational speed (peripheral speed) and wire descending speed (cutting speed), which are the operating parameters of a mono-wire cutting machine, on unit wear and unit energy, which are the performance parameters in mono-wire cutting. By using the obtained results, cuttability charts for each natural stone were created on the basis of unit wear and unit energy values, cutting optimizations were performed, and the relationships between some physical and mechanical properties of rocks and the optimum cutting parameters obtained as a result of the optimization were investigated.     

Investigation on the usage of different rock aggregates as abrasive materials in natural stone aging process

The process of giving an antique look, a worn and “old” appearance, to natural stone surfaces, which can be observed by abrasion in natural ways through a long time, is called artificial aging. Natural stone processing facilities that involve mass production usually prefer vibration aging machines. This study examines the utilization of various rock aggregates and abrasive residuals instead of synthetic abrasives used in aging machines. Natural stone samples with different properties were aged in a vibration aging machine using andesite, granite, sandstone, pebble stone, abrasive stone residuals, and ceramic abrasives. At the end of the study, the aging performance of different rocks was determined; granite was found to be the most effective. Rock aggregates were ranked in terms of their abrasiveness (aging) performance, from the most effective to the least effective as: granite, ceramic abrasive, sandstone, andesite, pebble stone, and abrasive stone residuals. It was observed that rock aggregates can be used in the aging process instead of synthetic ceramic abrasives, with desired performance.     

Influence of physico-mechanical properties of Indian dimension stones on cutting rate of diamond wire saw

Cutting performance of diamond wire saw is a key factor influencing mine planning, production scheduling, and equipment selection for dimension stone quarries. It is normally measured in terms of cutting rate. Rock samples collected from various granite and marble quarries in India were tested in laboratory to determine their physico-mechanical properties. Cutting rate of diamond wire saw was measured in the field studies during the actual cutting process in quarries. Using these laboratory determined properties and the cutting rate, a multiple linear regression model has been developed to predict the cutting rate of diamond wire saw. Physico-mechanical properties of rocks determined in laboratory are used as independent variables and cutting rate as predictor variable in the regression model. The study indicates that the cutting rate increases with a decrease in most of the hardness and strength parameters of rock. The final model is tested for its goodness of fit indicating a significant linear relation between cutting rate and physico-mechanical properties, namely tensile strength, slake durability index, and Cerchar hardness index with regression coefficient of 94%. The resulting model can be used suitably for different types of hard to medium hard and soft dimension stones. The generalized model for estimating the cutting rate becomes a handy tool for mining engineers to work out operating efficiency, expenses, planning etc. of the dimension stone block cutting.     

Application of statistical methods for predicting uniaxial compressive strength of limestone rocks using nondestructive tests

Uniaxial compressive strength (UCS) of an intact rock is an important geotechnical parameter for engineering applications. Using standard laboratory tests to determine UCS is a difficult, expensive and time-consuming task. The main purpose of this study is to develop a general model for predicting UCS of limestone samples and to investigate the relationships among UCS, Schmidt hammer rebound and P-wave velocity (V _P). For this reason, some samples of limestone rocks were collected from the southwestern Iran. In order to evaluate a correlation, the measured and predicted values were examined utilizing simple and multivariate regression techniques. In order to check the performance of the proposed equation, coefficient of determination (R ²), root-mean-square error, mean absolute percentage error, variance accounts for (VAF %), Akaike Information Criterion and performance index were determined. The results showed that the proposed equation by multivariate regression could be applied effectively to predict UCS from its combinations, i.e., ultrasonic pulse velocity and Schmidt hammer hardness. The results also showed that considering high prediction performance of the models developed, they can be used to perform preliminary stages of rock engineering assessments. It was evident that such prediction studies not only provide some practical tools but also contribute to better understanding of the main controlling index parameters of UCS of rocks.     

Multi-criteria analysis for the identification of waste disposal areas

The municipality of Cachoeiro de Itapemirim (ES) is currently the largest domestic producer and exporter of marble and granite in Brazil. The processing of the rock, especially the sawing results in a large volume of waste, including the abrasives used during sawing and the off-cut pieces. Presently these waste products are disposed of without proper environmental protection and cause pollution to surface water and groundwater resources, including silting, an increase in hardness and increased aluminium values in the groundwater. In order to minimize the harmful effects of these practices on the environment, a research project was undertaken to identify potential disposal sites for the generated waste. A multi-criteria approach was followed during which a database was compiled of all the companies generating waste products and also including a baseline environmental study of the region, integrated analysis (multi-criteria analysis) of the restriction factors and the preliminary identification of possible disposal sites. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reliability of Conventional Settlement Evaluation for Circular Foundations on Stone Columns

The unit cell idealization has been long adopted in the settlement prediction of stone column-reinforced soils. This paper tests the accuracy of this modeling concept against trusted settlement values of engineering foundations. It is believed that in order to bestow the outcome of this study adequate generality different soil properties and foundation geometries need to be considered. It was, nevertheless, found impracticable to collect field settlement records for all the analyzed cases. The authors, therefore, appealed to the back analysis concept to construct a reliable mathematical model, calibrated against settlement records of full-scale field load test. This model, which is capable of reproducing the real field settlements, is then employed as a generic tool to obtain trusted settlement values for a variety of cases with essential geometrical similarity. The investigation revealed that the unit cell analysis may, in some cases, lead to erroneous estimation for the settlements of foundations with limited extents. Correction factors, dependent on the treated soil properties as well as the foundation size, are introduced.     

北京大理岩物理力学参数的相关性研究

北京有大量采用房山大理岩制造的石质文物,这使得北京大理岩力学性质的研究对于科学指导文物保护和修复具有重要意义。但由于文物本体取样困难,难以获得其力学参数。因此本文对北京大理岩的物理、力学参数进行测试,通过建立物理参数和力学参数的回归方程,实现利用物理参数评价力学参数的目的。以北京大理岩中的青白石和汉白玉为研究对象,对8个边长为150 mm立方体试样进行施密特回弹测试,对40个Ф50 mm×100 mm的圆柱体试样进行里氏硬度、纵波波速测试和单轴压缩试验,得到了大理岩的回弹值、里氏硬度值、纵波波速与单轴抗压强度、弹性模量。分别以单轴抗压强度和弹性模量为因变量,选择单个或两个物理参数作为自变量建立回归方程。通过对比相关系数发现:（1）对于单个物理参数,单轴抗压强度与D探头里氏硬度值的相关性最好,而弹性模量与回弹值的相关性最好;（2）对于两个物理参数,单轴抗压强度（或弹性模量）都与回弹值和D探头里氏硬度值的组合相关性最好。     

Predicting the production rate of diamond wire saw using statistical analysis

Performance prediction of diamond wire saws is important in the cost estimation and the planning of the stone quarries. An accurate estimation of sawability helps to make the planning of the rock cutting projects more efficient. In this paper, the performance prediction of diamond wire saws in cutting carbonate rocks was studied on 14 different carbonate rocks in stone quarries located in Iran. Rock samples were collected from the quarries for laboratory tests. Uniaxial compressive strength, Brazilian tensile strength, Schmidt hammer value, and Los Angeles abrasion were determined in the laboratory. Performance prediction was evaluated using simple and multiple regression analyses. Finally, a new model was proposed for predicting the production rate of diamond wire saw. It was concluded that the production rate of carbonate rock using diamond wire saw can reliably be estimated using the developed model.     

Relationship Between Petrographic Characteristics and the Engineering Properties of Jurassic Sandstones, Hamedan, Iran

To study the relationship between engineering properties and petrographic characteristics, 20 rock samples were collected from Jurassic sandstones in the Hamedan region, western Iran. The specimens were tested to determine uniaxial compressive strength, point load strength index, tangent modulus, porosity, and dry and saturated unit weights. Samples were also subjected to petrographic examination, which included the observation of 11 parameters and modal analysis. Based on the results of a statistical analysis, polynomial prediction equations were developed to estimate physical and mechanical properties from petrographic characteristics. The results show that textural characteristics are more important than mineral compositions for predicting engineering characteristics. The packing density, packing proximity and grain shape are the petrographic properties that significantly affect the engineering properties of samples. Multivariate linear regression analysis was performed, employing four steps comprising various combinations of petrographic characteristics for each engineering parameter. The optimal equation, along with the relevant combination of petrographic characteristics for estimating the engineering properties of the rock samples is proposed.     

Newspapers as a validation proxy for GIS modeling in Fujairah,United Arab Emirates: identifying flood-prone areas

Prediction and control of blast-induced ground vibration is a matter of concern in mining industry since long. Several approaches ranging from scaled distance regression, different numerical methods to wave superimposition theories have been tried by many researchers for better prediction and control of blast-induced ground vibration. Signature hole analysis is one of the popular simulation methods to predict the ground vibration generated due to production blast. It superimposes the recorded signature hole waveform using a computer program to predict the production blast-induced vibration. The technique inputs the designated time of detonation of each hole and superimposes the waves generated by each hole to predict the nearest value of peak particle velocity and frequency of blast-induced ground vibration. Although a very useful approach, it requires a computer program to simulate the linear superimposition of waveforms. The simulation is not possible for every blast as it takes time and also is difficult for field engineers to simulate every time, whereas it is always easy for blasting engineers to adapt and use an empirical equation/approach for prediction and control of blast-induced ground vibration than simulation. In this paper, an attempt has been made to develop an innovative and simplified analytical approach of signature hole analysis. The simplified sinusoidal wave equation is obtained from recorded signature hole ground vibration waveform properties and is superimposed mathematically according to the multi-hole blast design to predict the production blast-induced ground vibrations. The validation of the developed approach was done in three different sites, and up to 15% more accuracy in prediction of the blast, vibrations are achieved in comparison with signature hole analysis prediction.

     

浅论欧泊的加工

欧泊具有特殊的变彩效应,是一种含水宝石和含有脉石的宝石,具有独特的加工性质,如硬度低、脆性强、怕热、色彩丰富、透明度多样、折射率极低、具有星光和猫眼特殊光学效应等.本文从欧泊的加工性质和品种分类出发,阐述了琢型设计和定向设计,着重探讨了欧泊的加工技巧,即在检查-定位-分割-预型-打磨-抛光加工全过程中自始至终处于冷加工状态,磨机、夹具和磨料之间的协同关系以及各种加工注意事项.最后从定向、琢型、比例、平衡性和抛光修饰度等几个方面探讨了欧泊的切工质量评价标准.     

Natural building stones

Natural stone due to its durable properties has been the choice of building materials since the very beginning of civilization. However, once stone is taken from its natural environment it begins to change to reach a state of equilibrium with its new environment. The polluted urban environment is a particularly hostile environment for natural stone and the effect on natural stone buildings, especially of historical or cultural significance, is a major cause for concern. Ongoing research into weathering studies is essential to provide a greater understanding of the processes that trigger stone decay and to ensure the implementation of successful stone conservation and replacement strategies.     

Effects of Rock Properties on Specific Cutting Energy in Linear Cutting of Sandstones by Picks

Summary. Specific cutting energy (SE) has been widely used to assess the rock cuttability for mechanical excavation purposes. Some prediction models were developed for SE through correlating rock properties with SE values. However, some of the textural and compositional rock parameters i.e. texture coefficient and feldspar, mafic, and felsic mineral contents were not considered. The present study is to investigate the effects of previously ignored rock parameters along with engineering rock properties on SE. Mineralogical and petrographic analyses, rock mechanics, and linear rock cutting tests were performed on sandstone samples taken from sites around Ankara, Turkey. Relationships between SE and rock properties were evaluated using bivariate correlation and linear regression analyses. The tests and subsequent analyses revealed that the texture coefficient and feldspar content of sandstones affected rock cuttability, evidenced by significant correlations between these parameters and SE at a 90% confidence level. Felsic and mafic mineral contents of sandstones did not exhibit any statistically significant correlation against SE. Cementation coefficient, effective porosity, and pore volume had good correlations against SE. Poisson’s ratio, Brazilian tensile strength, Shore scleroscope hardness, Schmidt hammer hardness, dry density, and point load strength index showed very strong linear correlations against SE at confidence levels of 95% and above, all of which were also found suitable to be used in predicting SE individually, depending on the results of regression analysis, ANOVA, Student’s t-tests, and R² values. Poisson’s ratio exhibited the highest correlation with SE and seemed to be the most reliable SE prediction tool in sandstones.