Manganese-ore Beneficiation Plants For India A
Manganese-ore Beneficiation Plants for IndiaP. 1. A. NARAYANANBig producers with large ore-reserves should put up their own beneficiation plants. But, since majorityof the manganese mines are small producers and have only medium or smal! ore-reserves, and sinceabout 50% of the manganese ores of India are of a complex nature requiring elaborate treatment,erection of custom type mills is the best way to their up-grading and conservation. The mills are tobe designed to suit the ore characteristics of each region and located in central places on a regional basis.CCORDING to the Industrial Policy Resolution(1956) of the Government of India, all industriesof basic and strategic importance should be in thepublic sector and the State should assume responsibility for the future development of these industries. Other industries which are essential andwhich require investments on a scale which only theState in the present circumstances could provide,have also to be in the public sector. Accordingly the Government of India has classified industriesinto three categories, having regard to the part whichthe State should play in each of them.In the first category where the future development of industries will be the exclusive responsibilityof the State, are included among other items thefollowing:—1. Coal and lignite2. Mineral oils3. Mining of iron ore, manganese ore, chromeore, gypsum, sulphur, gold and diamond4. Mining and processing of copper, lead,zinc, tin, molybdenum and wolfram5. Minerals specified in the schedule to theAtomic Energy (Control of productionand use) Order 1953.The second category comprises industries whichwill be progressively State-owned and in which theState will generally take the initiative in establishingnew undertakings but in which private enterprise willalso be expected to supplement the effort of theState. Under this category fall the following industries, among others :—1. All other minerals except 'Minor minerals'as defined under the Mineral ConcessionRules.2. Ferro-alloys, etc.The third category includes all the remainingindustries, and their future development will begenerally left to the initiative of the private sector.Manganese ores with which this paper is mostlyA MR. P. 1. A. NARAYANAN, Asst. Director, NationalMetallurgical Laboratory.INDIAN MINING JOURNAL, Special Issue, 1957concerned, fall within the first category from thepoint of view of mining and under the second category for production of ferro-alloys. Development ofnew manganese ore mines in future will thus be thesole responsibility of the State whereas processingand production of ferro-alloys could be undertakenby the State and the private sector on its own orwith State participation. As mining has beendefined to include ore-dressing operations also, erection of mineral dressing plants in future manganesemines may also be the sole responsibility of theState.The production of manganese ores in India forthe past five years is given in Table I.TABLE 1---PRODUCTION or MANGANESE ORE19511952195019531954882,929 1,292,375 1,462,2641,902,238 1,413,847MANGANESE ORESMines have been classified in Table II on thebasis of their production in 1954.TABLE IINo of mines producing over100,000 tons in 1954p r o d u cPIingbetween100.000 & 50,000producingbetween50,000 & 25,000„ producingbetween25,000 & 10,000p r o d u cingbetween10,000 & 5,000producing below 5,000 tonsProductionNil527.1613.91822.42412.839623.8--- -449100.0Table II indicates that except for a few big producers the rest of the output is from a large number ofsmall mines, whose individual ore-reserves and capacity to finance modern beneficiation plants cannot23
be that qualified mining engineers are not availablein sufficient numbers to cope with the heavy demandat present, but it is expected that in due course thiswill be remedied.So, for proper conservation of manganese as wellMINING AND DRESSINGas all other ores in general, the following methods.Except for two or three mines which are worked are suggested:—by the underground method, all the rest are surface1. Employment of qualified mining engineersworkings operated by the open-cut method. Twoor geologists in-charge of all miningof the open-cut quarries have been mechanized withoperations.power shovels etc., while all the rest employ manualStopping selective mining which is emlabour. There are two types of deposits which areployed at present in almost all the mines.mined for manganese : (i) lloat ore, and (ii) bedded3. Fixing a ceiling on dividends that can bedeposits.paid by mining companies to their shareOre lumps dislodged from the parent mass byholders, to enable their resources to beprocession of disintegration are drifted down hilldiverted towards better development ofand, form subsidiary mass constituting float ore.the mines.Mining of float ore involves digging up of the depo4. Putting up beneficiation plants to treatsit, hand screening for removal of fines and handthe low-grade ores, or the rejects obtainedjigging of the gravel after suitable sizing. Jiggingafter hand picking the high-grade concencan eliminate the light gangue present in the ore. buttrate from the run-of-mine ore.not the ferruginous and garnetiferous minerals. TheMethods 1 and 2 are too well-known to need anyjig concentrates often contain interlocked gangue further explanation.and as no crushing is done with this material, theseRegarding method No. 3, namely fixing a ceilingconcentrates are not always of the required purity, on dividends, the author is aware that this will meetfor production of standard grade ferro-manganese. with strong opposition from capitalists and the inOnly such of the deposits of float ore which contain vesting public, but it is to be noted that mineralsquartz and other light gangue and which yield high constitute the wasting assets of a nation and thatgrade jig concentrates without any crushing. are once they are mined and removed, they canont bebeing worked, though low grade concentrates obtain- produced again like agricultural commodities. Ined by this method, are also marketed at low prices. this connection, it may not be out of place to stressThe bedded deposits which are massive and well the need of reviewing as often as market and otherdefined or sometimes lenticular in character, are conditions warrant, the 'pay grade' of ore, whichblasted, reduced to a suitable size and the coarse never remains at any particular level. The 'payfraction alone hand picked. It is obvious that only grade' of ore that can be mined depends on variousthose deposits or portions thereof which yield a factors such as (i) price of the commodity. (ii) minmarketable grade of concentrate are exploited at ing conditions, (iii) availability of power, labourpresent. leaving the low-grade- deposits in situ un- etc. (iv) availability of rail, road and steamer comtouched or in the dumps. Fines below the size suit- munications, (v) scale of operations, and (vi) oreable for hand-picking, produced during the working reserves.of bedded deposits, also invariably go to waste. AsThese are sonic of the important points for conwill be shown later, not all ore deposits lend them- sideration, before starting of mining and processingselves to hand-picking. in view of the intimate operations. Once the operations have commenced,association of gangue with the manganese minerals. the 'pay grad& is governed primarily by marketCONSERVATIONconditions. If the price of the commodity remainsThus there is considerable wastage of ore in the at a higher level than was anticipated, the 'paypresent system of mining, handling and dressing. It grade' of ore that can be mined will be loweris estimated that for every ton of concentrate pro- enabling even lower-grade ores to be mined withduced, an equal amount goes to waste in the form profit. Under these conditions. poorer ores shouldof low-grade ore and fines, which could all be treated be increasingly mined. instead of mining only the by modern ore dressing methods for production of comparatively higher-grade ore. This will considerhigh-grade concentrates. One of the primary causes ably assist in the proper conservation of mineralcontributing to the colossal wastage of mineral wealth. This aspect, which is not well appreciated.wealth is the non-employment of trained mining has to be brought home to the mineral industry.engineers and geologists in the manganese mines. Profits accruing during prosperous days should beThough the Mineral Conservation and Development partly utilised for developing the mines and creatingRules (1955) stipulate that all mining operations reserves to fall back upon during the lean years,should be in charge of qualified personnel, mines instead of freely distributing the entire profits to theare still worked by not wholly qualified men. It may shareholders and becoming easily vulnerable tobe expected to be high. Out of the total productionof 1,413,847 tons, 50.6% is contributed by MadhyaPradesh, 24.5% by Orissa, 11.5% by Bombay, 6.2%by Mysore, 4.1 yo by Andhra and 0.2% by Rajasthan.24INDIAN MINING JOURNAL, Special Issue, 1957'
market fluctuations. This is applicable to the entiremining industry, and not confined to manganesealone, though the ups and downs have been rathertoo steep for manganese ore, forcing most of themines to close down during the slump periods.PUTTING UP BENEFICIATION PLANTSNext comes the most important method for conservation of manganese ores, namely putting up ofbeneficiation plants to treat the low-grade ores aswell as rejects obtained after hand-picking. Thisaspect has received considerable attention at theNational Metallurgical Laboratory for the past sixyears. Manganese ores from the important occurences in India have been tested at the MetallurgicalLaboratory to work out the best method of concentrating them ; and particulars of the 19 samples investigated so far are given below : —Madhya Pradesh.—(i) Tirodi mines, Balaghat ;Netra mines, Balaghat ; Miragpur mines,Balaghat ; (iv) Mansar mines, Nagpur ; (v) Kachidhana mines, Chhindwara.Orissa.—(i) Keonjhar ; (ii) Siljora, Keonjhar ;(iii) Sagur, Keonjhar ; (iv) Barajamda, Keonjhar.Bombay.— (i) Shivrajpur, Panchmahal ; (ii) NagriJoida, Supa Petha, N. Kanara ; (iii) D'grade ore fromNagri Joida, Supa Petha, North Kanara.Andhra.—(i) Salur, Srikakulam ; (ii) KodurKodur mines, (Elluvial) ; (iv)mines, (Bed Ore) ;Chipurupalli.Mysore. —(i) Sandur, Bellary ;Rajasthan.—(i) Kamji mines, Banswara ; (ii)Kalakunta etc. Banswara.The results of our investigations have revealedthat no two manganese ores are alike in their characteristics. But from the point of view of mineraldressing depending upon the types of gangue associated with the manganese minerals and their degreeof association, the ores in general could be classifiedinto four groups : Simple Ores ; Ferruginous Ores ;Garnetiferous Ores ; and Complex Ores.Simple ores contain quartz, felspar, clay andmicaceous minerals, amphiboles, pyroxenes, baryte,etc. as the common gangue. The manganese mineralsare free from gangue at a coarse size. Such ores areeasily amenable to beneficiation by simple processeslike washing, heavy media separation, jigging, tabling and magnetic separation.Ferruginous ores contain generally hematite andhydrated iron oxides as the major gangue. Whenconditions are favourable, the former can be eliminated by a patented process involving washing anddirect high intensity magnetic separation. In thecase of ferruginous ores in general, the ferruginousgangue can be separated by a method based on reduction roast which converts it to magnetite orv-hematite, and followed by magnetic separation.An interesting feature of this method is that themanganese concentrate is an ideal raw material andINDIAN MINING JOURNAL, Special Issue, 1957in some respects superior to ordinary high graderun-of-mine ores for the production of standardgrade ferro-manganese. The strongly magneticiron-rich product carrying some manganese can bevaluable as manganiferous iron ore.Garnetiferous ores are those containing garnetsas the major gangue, the elimination of which is notfound possible by gravity or magnetic methods ofseparation. However electro-static separation bringsabout a good separation of garnets from the manganese minerals. Quartz, if present can also beeliminated along with garnet as a non-conductingfraction. It is found possible in some cases to floatselectively the garnets from the manganese mineralsby employing cationic reagents.Complex ores are those in which either thegangue consists of different types of minerals or is inintimate association with the ore minerals necessitating thereby a complicated beneficiation procedure.They contain sometimes several of the undesirableconstituents like silica, alumina, iron and phosphorus—the elimination of all of which requires elaboratetreatment. The concentrates obtained fall short ofthe standard requirements in one constituent orother, which however can be made up by blendingwith appropriate ores or concentrates.The classification done above is not claimed tobe complete. And it is not as rigid as it appears toshow. The first three however, broadly indicatesthe main gangue present in the ore and the treatmentnecessary for each of the groups. Evidently complexores are meant to include ores falling under morethan one of the first three groups or when the oresrequire extremely fine grinding before they can beconcentrated.Phosphatic ores have not been classified as suchinto a separate group, because high phosphorus(over about 0.2% P) has been found to be presentin simple, garnotiferous as well as complex ores. Ifphosphorus is present as a mineral which is liberatedat a size coarser than about 100 mesh, magneticseparation or flotation could be employed for theirseparation. One remarkable thing about ferruginousores is that they have been invariably found to bequite low in phosphorus.Out of the 19 samples investigated in detail atthe National Metallurgical Laboratory, two fallunder Simple ores, three under Garnetiferous, fiveunder Ferruginous, and nine which represents nearlyhalf fall under Complex. If these could be taken tofairly represent all the important occurrences inIndia, very few ores are of a simple type requiring asingle inexpensive treatment. Plants to treat suchores can be installed with a capital outlay less thanthat required for other types of ores, for the samecapacity. Gametiferous ores requiring flotation orelectrostatic separation need a more costly plant. Aplant for reducing roast and magnetic separationneeded for ferruginous types of ores, is also expected25
to be as costly as for garnetiferous ores. The costliest of all the plants are the ones to treat complexores, which fall under two or more of the abovementioned groups.Custom mills are ore-beneficiation plants generally designed to treat ores of a particular region.As no two ores are alike even in the same region,a plant to treat ores on a regional basis, has to beequipped on an elaborate scale and this increases thecapital cost. Custom mills are therefore to be preferred only when conditions are not favourable forinstallation of individual mills to treat particular ores.Mines have therefore been classified below intofour categories on the basis of their low-grade orereserves, the financial resources of the mine ownersand the complexity of the ores. The author's suggestions are also given as to who should put upbeneficiation plants in each of the cases, and to whatextent the State might offer assistance.Category I. Mill for big producers with largeore-reserves.-1f a particular deposit has sufficientore reserves to justify the putting up of a mill, theowners of such property should themselves take theinitiative to put their own plants. Sending the oresfrom such mines for treatment to a custom millthough there may be one in the region, will be verycostly in the long run.Category 2. Mill for medium or small producers with large ore-reserves.—The question thatarises is whether medium or small-scale producerswith large ore reserves have financial resources toinstall their own beneficiation plants. It has beenshown earlier that the number of small mines producing less than 10,000 tons per year and contributing 36.6% to India's production, is quite considerable(about 426) of which some must be having orereserves to justify installation of a mill. These minescannot all be expected to have the financial resourcesto put up their own mills, inspite of their havingsufficient ore reserves. Though, under the MineralsConservation and Development Rules, it is theresponsibility of the mine owners to beneficiatetheir low grade ores, practical considerations pointto the desirability of Government assistance in putting up ore dressing plants and if necessary, controlover such of the mines which receive Governmenthelp.Category 3. Mill for small producers withmedium size reserves.—Next comes another category of mines which includes a large majority of theproducers, who do not have sufficient ore resourcesof their own to justify individual mills, but couldjoin hands and start one or more custom millsamong themselves with State assistance to treat theirores. Such an arrangement will be all the moreattractive in places which have already the sametype of ore, for example, Orisa and North Kanarawhere the ores are mostly ferruginous in character26requiring reduction roast and magnetic separation.Even if such ores are high in silica, high intensitymagnetic separation can eliminate this gangue.Ores of these regions with their particularly lowphosphorus lend themselves to the production ofconcentrates suitable for very high grades of ferromanganese. The proposal for custom mills will alsobe most helpful for treating complex ores whichcan be economically beneficiated, but which needelaborate equipment. As indicated earlier about50'po of the Indian manganese ores come under thiscategory and consequently, there is considerablescope for putting up mills of the custom type.Mines falling under this category will necessarilyneed the financial and technical assistance of theState in the installation of ore-dressing plants. Inthe interest of the manganese ore industry and witha view to translate the conservation policy intopractice, the State should take the initiative in bringing these small producers together and renderingnecessary assistance to start custom type mills whichis the best solution to the small producers, withlimited reserves of ore even of a complex nature.Category 4.-Complex ores which need a complicated treatment or involve very fine grinding andconsequently low recoveries, might preferably bebeneficiated by pyrometallurgical or chemicalmethods.PROPOSED FERRO-MANGANESE PLANTSThe second Five Year Plan target for ferromanganese production is 1.60,000 tons to beattained by 1960-1961 and licenses have been issuedto nine firms for his purpose. The amount of highgrade concentrate required for producing the abovetonnage of ferro-manganese will be about 320,000tons. The information available at present indicatesthat only the plant to be set up at Garividi inAndhra will beneficiate their ore from the start. Itis reported that the plants to be located at Joda(Orissa) and Dandeli (Bombay) will utilise theirhigh-grade hand-picked ores to start with, till theirbeneficiation plants are installed. Nothing is knownabout the plans of the other licensee. As productionof standard ferro-manganese is difficult to maintainfrom hand-picked ore alone from a mine, it isadvisable to use beneficiated product of the requiredspecification. Such practice not only enables utilization of the off-grade ores produced during mining operations, but ensure production of high-gradeferro-manganese suitable even for export. Thesooner this aspect is realised by the prospectiveferro-manganese producers, the better.SINTERINGManganese concentrates produced after beneficiation will invariably be in the form of fine powder,except in the case of co
of low-grade ore and fines, which could all be treated by modern ore dressing methods for production of high-grade concentrates. One of the primary causes contributing to the colossal wastage of mineral wealth is the non-employment of trained mining engineers and geologists in the mangane
38.33%, respectively, when the grade of 0.074 mm fraction with 80% of manganese ore. As a result of the shaking table tests, the manganese content in the concentrate was 35.84% and, the metal recovery and yield were 50.57% and 24.43%, respectively, for the manganese ore fraction
dressing”, “mineral dressing” and “minerals beneficiation”. For most metalliferous ores produced by mining op-erations, beneficiation is an important intermediate step in the transformation of natural ore to pure metal [1]. Since the goal of every mineral processing operation
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process. As shown in Fig. 1, the beneficiation process mainly comprises the sub-processes of grinding, separating and dewatering. 2.2.1 Grinding Grinding is a sub-process of finely grinding ore in advance, such that the ground output can be physically separated into iron ore and impurities in the downstream sub-process. In many cases, an
Un PT a 20 ore, per le prime 5 ore di supplementare fatte in una settimana la maggiorazione è al 15%, per le successive 15 ore la maggiorazione è al 18%. Un PT a 30 ore, per le prime 7,5 ore è al 15%, per le successive 2,5 ore al 18%). Valore complessivo rinnovo contrattuale TEC e TEM:113 SINTESI MODIFICHE ARTICOLO PER ARTICOLO
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conforms to the ISO 14001 Standard.1 While ISO 14001 has existed for more than 20 years, the changes adopted by the International Organization of Standards in 2015 are the most sweeping since the standard’s inception. Organizations certified to the former version must incorporate the new requirements by September 15, 2018. The articles that follow examine key changes in the ISO 14001:2015 .
