Column flotation technology for the beneficiation of coking and non-coking coal fines

The importance of coal is bound to increase for the coming years with the growth of coal consuming industries. Power sector is the most potential consumer of the non-coking coal and for coking coal iron & steel sector remains the major consumer. In future, coal gasification which is successfully adopted in China, an advanced coal-based power generation technology has the potential to provide higher generating efficiency and can be adopted to efficiently burn India’s high-ash coals. In the present study investigations are carried out on coal fines for both coking and non coking coals by conventional and column flotation techniques to suit industrial applications. Coking coal sample is taken from Jamadoba area in Jharkhand and non-coking coal is drawn from coal belt in Central Coal Fields, Jharkhand. For both the coals detailed studies are in progress for optimizing the reagent consumption and to establish the feasibility of column flotation technology for producing low ash concentrates with reasonably high recoveries

Recovery of values from tailing ponds of iron ore washing plants

Most of the Iron ore washing plants set up in India in the earlier days consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers. In this classical approach, iron values were lost in the form of fines and utrafines into the tailing ponds as they had little commercial value in those days and accumulated in huge quantities over the years. As the high grade deposits are getting exhausted and the demand for high grade finer material for pellet making is ever increasing, focus is shifting towards recovering the values from the erstwhile tailing ponds by column flotation. This is also supposed to mitigate to certain extent the environmental problems caused by the ever expanding and unmanageable tailing dams. A case study is presented wherein a composite sample is prepared from samples drawn systematically from multi - locations in a sprawling tailing dam. Laboratory scale column flotation tests on this composite tailings sample, basically originating from two operating iron ore beneficiation plants of JSW Steel Ltd., one of the leading producers of steel in India, are found to be encouraging. De-sliming followed by reverse and cationic flotation tests using flotation column resulted in the concentrate of 61.88% Fe, 4.81% SiO2, 2.52% Al2O3 and 3.30% loss on ignition (LOI) from the tailings analysing 57.86% Fe, 7.10% SiO2, 3.52% Al2O3 and 6.14% LOI with 52% weight recovery. The causes for the quality improvement could be attributed to de-sliming of unliberated ultra fines of kaoline and hydrated iron oxides and their further reduction by efficient flotation process. The process and the cationic collector developed for this purpose are adopted in the new flotation plant created to treat these tailings

Eco Friendly and Cost-Effective Reagent for Coal Flotation

Conventionally, diesel in combination with a frother is used widely in flotation of coal fines. With the continuous price escalation of petroleum products and their negative impact on environment, attempts were made to formulate an eco-friendly single reagent to replace diesel-frother system without affecting the flotation performance. Laboratory flotation tests were carried out, on a coking coal sample from eastern India, that analyzed 25.67% ash and 53.97% fixed carbon using a series of reagents developed. Among them, the performance of Sokem 590C derived from a vegetable oil was found to be encouraging. Concentrate assaying 11.77% ash and 66.40% fixed carbon was obtained with yield of 56.57%. Moreover, the reagent is biodegradable and eco friendly. Based on favorable kinetics and encouraging test results, plant trials were conducted at a coal preparation plant and the superiority of this reagent was demonstrated

Single reagent for coal flotation

Froth flotation is widely used for the beneficiation of fine coal and collectors are important for the effective separation in flotation. Conventionally, diesel in combination with a commercial frother is used in most of the coal washeries. With the escalating costs of petroleum products and their negative impact on environment, attempts were made to formulate an eco-friendly single reagent to replace diesel-frother system without hindering the flotation process performance. NML-Madras Centre in collaboration with M/s Somu Organo Chem Pvt Ltd, has been working on the formulation and evaluation of flotation reagents. Laboratory flotation tests were carried out using series of single reagents on a coking coal sample from Jharia region in the eastern part of India with an ash content of 24.9%. The best among the single reagents, Sokem 590C, yielded a float of 56.57% at 13.97% ash in the bench scale laboratory test. Based on encouraging results of flotation tests and kinetics studies, plant trials were conducted at a coal preparation plant in eastern India. The results of plant trials using this single reagent, Sokem 590C, are highly encouraging and economical as compared to diesel-frother system and this single reagent is non-petroleum based and biodegradable

Fine coal beneficiation by pilot column flotation

Beneficiation of coal fines with high ash content was attempted in an operating coal preparation plant by retrofitting a 0.5 m diameter pilot plant scale flotation column in the circuit. The collector and frother dosage were optimized as 0.680 kg/t and 0.058 kg/t respectively. At these reagent conditions the operating parameters of pilot scale flotation column were also optimized. The maximum yield of the froth obtained was 67.5% at the targeted ash level of 14% from a feed of 25% ash content. This was obtained at the operating parameters of 0.85 cm/s superficial air flow velocity, 0.57 cm/s superficial feed slurry velocity and 600 mm froth height. The performance of flotation column was found to be marginally better than that of the conventional flotation cells in the washery. Also, advantages such as low operational, maintenance and energy costs and operational flexibility in the case of flotation column could lead to financial accruals over a long run

Single reagent for graphite flotation

Generally, diesel and frother are used as reagents in graphite flotation. With the escalating cost of petroleum products and their negative impact on environment, attempts are made to formulate an eco-friendly single reagent to replace the diesel-frother system without affecting the flotation performance. CSIR-NML Madras Centre in collaboration with M/s Somu Organo Chem Pvt Ltd., India, has worked out the formulation and evaluation of single reagent on a low grade graphite ore sourced from eastern India. The petrography studies indicate that the ore primarily consists of quartz and graphite with minor quantity of mica and analyzing 87.85% ash content. The ore is crushed in stages followed by primary coarse wet grinding to 242 µm (d80). Rougher flotation is carried out in Denver flotation cell with a view to eliminate gangue as much as possible in the form of primary tailings with minimal loss of carbon. Regrinding of rougher concentrate to 216 µm (d80) is opted to improve the liberation of graphite values. This approach involving a primary coarse grinding and regrinding of rougher float followed by multi-stage cleaning using this single reagent is found to yield better recovery and grade when compared with that of the dual reagent system. A final concentrate of 12.03% weight recovery with 3.22% ash could be achieved. Based on encouraging laboratory studies using the single reagent, plant trials were carried out. From the cost benefit analysis, this single reagent proves to be an economically viable in place of diesel-frother for processing low grade graphite

Assessing unrealized yield potential of maize producing districts in India

The projected demand of maize production in India in 2050 is 4–5 times of current production. With the scope for area expansion being limited, there is need for enhancement of yield. This calls for identifying areas where huge unrealized yield potential exists. With a view to address the issue, the present study delineates homogeneous agro-climatic zones for maize production system in India taking district as a unit and using the factors production, viz. climate, soil, season and irrigated area under the crop. There are 146 districts in India that grow maize as a major crop. They were divided into 26 zones using multivariate cluster analysis. Study of variation in yield between districts within a zone vis-à-vis crop management practices adopted in those districts was found useful in targeting the yield gaps. These findings can have direct relevance to the maize farmers and district level administrators

Search for physiologically active compounds. Part XXIV. Synthesis of 7, 8-furano, pyrono and 3-methyl-4-phenylcoumarins

7-hydroxy-3-methyl 4-phenylcoumarin and α-methyl dihydrofurano, α and γ-pyrono ring systems have been built on 7, 8-position of 4-phenylcoumarin. The bacteriostatic activity of these compounds as well as that of mammeisin and mesuol isolated from Mesua ferrea seeds has been evaluated. Structure-activity relationship among these compounds is discussed

Reaction of some substituted 2-allylphenols with 2,3-dichloro-5, 6-dicyano-1,4-benzoquinone (DDQ) - a new method for the synthesis of coumarins

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