Browsing by Author "Vardhan, Harsha"

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Design and Development of Flexible Screen for Processing Industries and its Performance Prediction using Machine Learning Techniques
(National Institute Of Technology Karnataka Surathkal, 2023) S, Bharath Kumar; Vardhan, Harsha; M, Govinda Raj
In the material processing industry, screening is one of the crucial physical separation methods to separate the undersized fine particles from the oversized coarse particles. The availability of low-grade coal and iron ore with high impurities has urged the improvisation of processing equipment such as screening machines with higher efficiency without utilising water. Previous studies showed that wet processing of coal and iron ore was carried out with enormous quantities of water and also required a water treatment circuit in the plant to treat the tailings. Dry processing has significant merits in preventing water consumption, eliminating waste, and tailing water treatment. The major problems of the existing dry processing linear vibratory screening machine are lower efficiency caused by the screen clogging, high velocity, reduced residence time, and inflexibility in changing the angular position and frequency of the screen. The efficiency of the existing linear vibrating screen available at the JSW (Jindal Steel Works) steel plant, as well as that available in the Department of Mining Engineering, NITK Surathkal (lab scale), was around 65.00%. So, a new screening machine was designed and developed to overcome all the limitations of the existing linear vibratory screening machine. The new screening machine was developed with a circular mode of vibration for dry screening of moist coal and iron ore of size fraction −4mm + 0 mm. A screen mesh of 2 mm aperture size was used to separate the fine coal and iron ore particles of size fraction −2 mm + 0 mm individually. The new screening machine has the flexibility to vary the operational parameters, such as the angle in an upward sloping direction and the vibration frequency of the screen, and it can work as a feeder. Experimental investigations were conducted at the JSW R&D laboratory to assess the efficiency of screening coal and iron ore of varying moisture content of 4%, 6%, and 8% in the new screening machine. Before the screening, the angle and frequency were set by adjusting the angle bolts and frequency drive, respectively. During the screening, the samples were fed to the screen at 8.33 kg/min and undersize particles were icollected. The collected samples were weighed, and the screening efficiency was calculated for coal and iron ore samples. The test results showed that the screening machine could provide higher efficiency for screening iron ore than coal material. Further, the screening efficiency of coal and iron ore was predicted using a machine learning (supervised learning) prediction model such as polynomial regression and backpropagation artificial neural network (ANN) models. The results showed that for all experimental conditions, compared to the second-order polynomial regression modelling, the ANN modeling was a better mathematical modeling technique suitable for predicting the screening machine’s performance. Further, the residual analysis of each prediction model was analysed and validated using a normal probability plot and histogram. Additionally, the developed screening machine’s operational parameters were optimised using the Taguchi L27 Design of Experiments technique to obtain a high response parameter, i.e., screening efficiency. For the optimisation study, the operational parameters considered were moisture content, angle, and frequency. The Taguchi L27 optimisation results yielded a higher screening efficiency of 84.40% for coal and 94.53% for iron ore. Furthermore, the Pareto chart and normal effect plot were developed using a fractional Design of Experiments (DOE) to evaluate the significant operational parameter for the screening machine. The results of the fractional Design of Experiments on coal and iron ore show the moisture content as the most significant operational parameter, followed by the angle and frequency. Additionally, the feeding performance of coal and iron ore was improved by transforming the screening machine into a feeding machine by replacing the screen mesh with a thin solid plate. The results showed that the developed machine could be utilised as a multifunctional machine for efficient screening with less clogging and also as an efficient feeder.
Design and Development of Hydro-Squeeze Classifier Assisted Grinding Ball Mill for Narrow Size Particle Separation
(National Institute of Technology Karnataka, Surathkal, 2022) H, Harish; Vardhan, Harsha; Raj, Govinda
In the iron and steel industry, the production of desired particle size distribution (PSD) for pellet feed making from the iron ore is very difficult. This study is carried out to achieve desired pellet feed particle size distribution from the iron ore. The iron ores have been collected from three different sources (mines in Karnataka state) and milled. Iron ore obtained from different sources differ in their chemical and physical properties. These variations make the process of grinding a difficult task. The work carried out in this context focuses on three different samples of iron ore, viz., High Silica High Alumina (HSHA), Low Silica High Alumina (LSHA), and Low Silica low Alumina (LSLA). The grinding process for all the three iron ores is carried out individually in Bond‟s ball mill and the total retention time taken by each iron ore sample is calculated. The present investigation focuses on utilizing the calculated retention time of the iron ore as a standard grinding reference time to the laboratory ball mill for optimizing the grinding time of each ore. The desired P80 (150 μm) with an acceptable range of hematite liberation (>75%) was obtained in laboratory ball mill after reducing 6 min from the total retention time taken in the Bond‟s ball mill. The blend as iron ore feed sample was prepared by using High Silica High Alumina, Low Silica High Alumina, and Low Silica low Alumina iron samples, in various proportions. The iron ore blend feed sample is analyzed in the Optical Microscope (OM) and QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) to understand the PSD and percentage of hematite liberation. A new approach was adapted to identify the retention time (RT) of the iron ore blend in the mill, and the total retention time (TRT) taken for the blend sample in the Bond‟s ball mill (BBM) was considered as the reference grinding time for milling in the Laboratory Ball Mill (LBM). The desired PSD (-150 μm) with acceptable hematite liberation was achieved at an optimal grinding time of 7 min in the LBM. ii The discharge end design of a ball mill plays an important role in discharging the desired particle sizes (-150 + 10 μm) and the percentage of recirculating load from the discharge end of the ball mill. In continuous wet ball mills, the composition of feed (hard ore or soft ore) to the mill varies continuously, leading to uncontrolled grinding in the mill. In view of this, a new design of the discharge mechanism has been implemented to remove the ground particles of desired particle size fraction with minimum recirculating load (+150 μm). The results from the discharge end with lifters (closed and open) show that the particle size fraction obtained from the discharge end has a maximum percentage of desired particle size fraction when the mill is operating at 60% critical speed. Discharge end without lifters has an uncontrolled particle size distribution in the discharge and the percentage of desired-size particles discharged was found to be very less. Also, the percentage of the recirculating load is minimum in the case of discharge end with lifter design compared with discharge end without a lifter. Hence, a new design of lifters in the discharge end leads to the discharge of the desired particle size fraction with minimum recirculating load. A new ball mill hydro-squeeze classifier has been developed for particle size reduction and wet classification of different particle sizes. The mill classifier consists of milling and classification sections with a squeezing disc with a mesh of 150 μm. This study analyses the size of particles discharged from the ball mill and the efficiency of hydro-squeeze classifier in separating oversize particles from undersize particles. The ball mill hydro-squeeze classifier was tested at different iron ore feed slurry concentrations and the ball mill operating discharge end opening time. A significant increase in coarse particle discharge from the mill to the classification section was achieved at a higher (75%) slurry solid concentration. The squeezing of the slurry increases the recirculating load to the mill. The squeezing efficiency is maximum (84.8%) at a solid slurry concentration of 55% at a mill discharge opening time of 150 s. The separated particles in the hydro-squeeze classifier consist of 100% -150 μm particles. Further, these particles can be directly used for downstream processing without any classification. The results obtained are applicable for the pilot- iii scale development of a new ball mill hydro-squeeze classifier unit for wet grinding and classification process.
Experimental Investigation on Estimation and Prediction of Sound in Percussive Drilling
(National Institute of Technology Karnataka, Surathkal, 2013) Kivade, Sangshetty; Murthy, Ch. S. N.; Vardhan, Harsha
This research work was taken up with the objectives of developing general prediction models for the determination of uni-axial compressive strength (UCS), abrasivity, tensile strength (TS) and Schmidt rebound number (SRN) for sedimentary and igneous rocks using penetration rate and sound level produced during percussive drilling. To carry out this investigation fabricated pneumatic drill set-up on the laboratory scale was used. In the present work shale, dolomite, sand stone, lime stone and hematite were the sedimentary rocks, whereas dolerite, soda granite, black granite, basalt and gabbros were the igneous rocks used in this investigation. For all the above mentioned rocks their mechanical properties were determined as per the suggested methods of International Society of Rock Mechanics (ISRM). The laboratory investigation on all the sedimentary and igneous rocks using the drill set-up was carried out to find the penetration rate (mm/s) and sound level (dB (A)) produced by varying air pressure from 392 to 588 kPa, thrust from 100 to 1000 N and with varying drill bits and types (integral chisel drill bit: 30, 34 and 40 mm diameter, threaded (R22) cross drill bit: 35 and 38 mm diameter). The data generated in the laboratory investigation was utilized for the development of regression models for predicting rock properties like, UCS, abrasivity, TS, and SRN using air pressure, thrust, bit diameter, penetration rate and sound level. Further, regression models were also developed for predicting penetration rate and sound level using air pressure, thrust, bit diameter and rock properties as input parameters. In a similar way, i.e. utilizing the same input parameters for determining the rock properties and predicting the sound level and penetration rate, Artificial Neural Network (ANN) models were developed. A comparison was made between the results obtained using various regression models developed and the ANN models. Results of this investigation indicate that ANN models are superior over regression models.
Investigation and Assessment of Quality of Bricks Prepared Using Iron ore Waste
(National Institute of Technology Karnataka, Surathkal, 2017) Lamani, Shreekant Revachand; Vardhan, Harsha; Aruna, M.
Mining is the backbone of many countries economy. Iron ore mining plays a significant role in production of steel and other metals, but at the same time generates massive waste which pollutes the environment and brings other issues related to its storage and handling. Hence there is a need to develop a comprehensive plan for utilisation, storage of iron ore waste fines from the point of view of saving resources and sustainable development. Iron ore waste fine has low percentage of Fe2O3, hence it is discarded. Iron ore waste is dumped at relevant place as per the approved mining plan. It occupies large area within the lease boundary, degrades surrounding land and also deteriorates the environment. In general, any building materials are directly or indirectly prepared from the earth’s crust. The basic composition of building materials is nearly same as the composition of earth (i.e. silica, aluminum oxide, iron etc.). In the recent years, there has been a significant demand for building materials in India as well as all over the world. Therefore, it is imperative to use mining and mineral wastes in the production of bricks, paving blocks and other value added products which are used in the construction industry. Since the need for building materials is growing at an alarming rate, therefore in order to meet the demand for new buildings, new ways and techniques must be evolved for brick making. Manufacturing of building materials like brick, cement, steel, aggregates, etc. which are consumed in bulk quantities, puts great pressure on natural resources and are highly energy demanding. Therefore, the use of alternative material for brick manufacturing should be encouraged. Hence, there is a scope for utilizing mine wastes for the manufacturing of building material and other products. Mine wastes and tailing can be converted into bricks/paving blocks, which can meet the demand of brick in metropolitan cities for the next 30 years or even more. Similarly, utilizing the ironore waste tailings can fulfill the requirements of bricks for Karnataka State for many decades. Thus, there is great potential for utilizing mine wastes to manufacture building materials and products. The crux of this investigation was the possibility of making bricks by mixing iron ore waste fines from iron ore mines with other additives like cement and fly ash. In this investigation, the iron ore waste percentage (by mass) was varied from 65 to 90, whereas that of cement was varied from 0 to 30. The cement percentage was restricted to a maximum of 30 %, based on the study carried out by various other investigators. Similarly the fly ash percentage by mass was varied from 0 to 30. Iron ore waste fines were collected from the run-off of dumps from a large opencast mine of M/S. Sandur Manganese & Iron Ore Limited located in the state of Karnataka. A total of nine iron ore waste fine samples were collected from nine different locations in consultation with the mine management. However, samples collected from only six locations were considered for this study based on the chemical composition, especially the Fe2O3. Three samples where in Fe2O3 was more than 30 % was not considered as waste as they could be upgraded to iron ore in near future. Fly ash for this investigation was collected from Udupi Power Corporation Ltd. It was found that around 90 % of the collected iron ore waste fines were below 600 µ size. Hence, iron ore waste fines are directly suitable for preparation of non-fired bricks without going for any crushing, grinding or screening processes. The investigation revealed that cement can be readily used as an additive/binding material for preparing non-fired bricks from iron ore waste fines found in iron ore mines. These bricks comply with IS Standards IS 13757:1993 of class designation 3.5, which can be used in the construction of simple temporary and cheap structures which are not exposed to heavy rains. Bricks with 9 % cement content as an additive in brick making along with fly ash and iron ore waste fines will meet the desired compressiveiv strength as per BIS guidelines of 3.5 MPa with 28 days of curing period. With 10 % cement content in the brick with varying percentage of fly ash and iron ore waste fines, the bricks with several combinations attain the desired strength as per BIS standards much below 28 days (7 days, 14 days and 21 days) and therefore can be used as a construction material even without 28 days of curing the details of which are presented in this thesis. All the bricks prepared with 9 % cement content as binding material and with curing of 7 days and above meet the BIS standards of water absorption. Investigation has revealed that bricks prepared with below 9 % cement as binding material will deform once removed from the mould and will have very low compressive strength of the order of 0.55 to 0.67 MPa with 28 days of curing. Fly ash from thermal power plants should also be used along with cement and iron ore waste fines in brick making process. The fine fly ash particles improves the concrete pore structure thereby stimulating early strength development and also increases the compressive strength of bricks. Further addition of fly ash in the brick, makes the brick lighter. It was found that there is a significant reduction in weight of the bricks of around 0.5 kg by using fly ash compared to that of bricks prepared without fly ash. Hence, it is recommended to use fly ash in the process of brick making using cement and iron ore waste fines. Further, use of fly ash in making brick is environmental friendly too. It was found that the bricks prepared with 30 % cement, 25 % cement, 20 % cement, 15 % cement and 10 % cement costs ₹ 10, ₹ 9.20, ₹ 8.70, ₹ 7.80 and ₹ 7.20 per brick (excluding profit), respectively, which is substantially below the cost of fired compressed bricks available in the market (costing ₹ 15 per brick). As the cost figures arrived in this research work are based on the cost computation of prepared bricks on laboratory scale, it is anticipated that the cost figures may reduce further when the brick preparation is done on industrial scale. A number of regression equations have been developed for predicting compressive strength and percentage of water absorption of prepared bricks with different days of curing. These equations can be readily used to find out the compressive strength and water absorption of bricks with acceptable level of accuracy. Results on the investigation of the impact of chemical composition of bricks on its compressive strength has revealed that there is no proper relationship of it with total percentages of SiO2 and Al2O3 present in a brick. With increase in total percentage of Fe2O3 present in a brick, its compressive strength was found to decrease gradually. Hence, it is suggested to prepare non fired bricks from iron ore waste fines containing low percentage of Fe2O3 which is also desirable from the point of view of mineral conservation. However, further work needs to be carried out in this direction to confirm the above mentioned results.
Investigations on Performance of a Diesel Engine Operated with Raw Cardanol and Kerosene Blends
(National Institute of Technology Karnataka, Surathkal, 2019) Ravindra; Aruna, M.; Vardhan, Harsha
Worldwide diesel engines are the main source of power for heavy duty equipments in mines and other applications. Since the world crude oil reserves are depleting very fast, there is a need for alternative source. The biodiesel originated from animal fats or vegetable oils are the easier alternatives for diesel fuel, which can be utilised without much engine alterations. However, increased cost of the biodiesel due to the esterification process involved in the production of biodiesel is a limiting factor for vast usage of this alternative. In this research work, raw Cardanol extracted from cashew nut shell is tested as a diesel engine fuel without esterification. To reduce the viscosity of Cardanol, it was blended with kerosene. Experiments were carried out in a 3.5 kW four stroke single cylinder diesel engine using different blends of Cardanol and kerosene, such as BK10 (10% kerosene and 90% Cardanol), BK20% (20% kerosene and 80% Cardanol), BK30 (30% kerosene and 70% Cardanol), BK40% (40% kerosene and 60% Cardanol) as a fuel. Performance parameters such as brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature and the exhaust emissions of unburned hydrocarbon, carbon monoxide, oxides of nitrogen and smoke were measured and compared with diesel fuel. Effect of the engine operating parameters like, compression ratio, injection pressure and injection timing on the engine performance are also investigated. Using the taguchi method, the experimental results were optimised and BK30 blend proved as the most favourable blend for optimum engine performance with minimum emissions, under the following operating conditions: compression ratio - 18:1; injection pressure - 220 bar; injection timing - 24.5°BTDC; load - 12 kg. A fuel cost reduction by about 22% could be observed upon using BK30 biofuel blend as a replacement to diesel fuel in mine machineries. Invention of this novel biofuel blend increases the effective utilisation of Cardanol as a biofuel.
Rock Engineering Design Properties and Applications of Sound Level
(2013) Vardhan, Harsha; Bayar, Rajesh Kumar