Survey on Various Types of Noise and Methods for Noise Removal

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415 Copyright © 2011-15. Vandana Publications. All Rights Reserved.

Volume-5, Issue-4, August-2015

International Journal of Engineering and Management Research

Page Number: 415-419

Exploration for Mubda Chromite, Samail Wilayat, Sultanate of Oman

M.Rajamanickam1, Jose Ravindra Raj.B2, Sasikala.S3, Geetha.V4, V.Jothi5

1,2_{Assistant Professor, Department of Civil Engineering, Prist University, Trichy-Thanjavur Highway, Vallam, Thanjavur,}

INDIA

3,4,5_{Department of Civil Engineering,}_{Prist University}_,_{Trichy-Thanjavur Highway, Vallam, Thanjavur}_{, INDIA}

ABSTRACT

The chromite ores are used expansively for the

making of sodium chromate.The study area is situated in the southern part of Muscat, Oman. The fieldwork was carried

out for detailed investigations of Mubda geology,

geomorphology, and slope analysis using topographic data. The results obtained from the chemical analysis report as well as the geophysical method used for chromium mineral feasibility analysis properties of chemical grade chromite ores.The chemical results reveal that the parent rocks exposed in the given area of study have a higher chromite content.The chromite deposits are generally located in dunite bodies of variable sizes and shape. It is revealed that the entire area of the concession is prospective and has the potential of economic interest for chromite mining and trading.

Keywords— Chromite, geophysical, dunite, prospective

I. INTRODUCTION

The Sultanate’s mineral resource consist of chromium, silica, copper, dolomite, zinc, and iron, limestone, gypsum, gold,cobalt to name but a small number of mining activities engaged by Oman government. Numerous industries have developed up as part of the national development practice whichever trend have supported the mineral stratum contribution to the nation’s GDP as well as providing jobs for Omanis.In July 1991, the government established the Oman Chrome

Company (OCC), in whichever it purchase of 15 percent fraction. The surplus of the percentage are taken by the private sector.The OCC was formed to expand the country's chromite reserves estimated by the Robertson Group of Britain.The public offering of OCC shares reflects the government's official policy of encouraging private-sector participation in industry and manufacturing. This first phase of exploration was carried out based on the scope of works described in the proposal submitted to the Ministry of Commerce and Industry in the month of November of 2010.There are numerous researches on chnromite characterization and susceptibility occurrence [1][2][3][4] and [5] have been studied in different part of the world.The main objective of this study was to assess the economic potential of the Mubda chromite, as well as to come to a decision even if to go for another exploration of phase second or not for further detailed study.This report includes the survey results of the preliminary study. 1-1. Accessibility to the prospect area:

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Fig.1.Map showing 3dimensional Topography & Study

area

Table.1.Team of the geological survey:

1.2. Geological Survey Period:

The preliminary fieldwork in the given area of study was carried out from 01.04.2011 to 16.04.2011,a total period of 16 days.Table.1.Showing the UTM coordinates field survey location.

II. REGIONAL GEOLOGY

The geological domain in and around the concession area is dominated by the Ultrabasic igneous rocks (Ultramafites) consisting essentially of ferromagnesian minerals.They belong to the Samail Ophiolite which is a fragment of oceanic lithosphere originating from the ocean floor of the Neo-Tethys.The Samail oceanic crust was thrust over the Arabian Platform. Within the Neo-Tethys, the oceanic Samail Basin offshore of Oman was an area of accretion where primary crust was formed at a spreading ridge. Sea-floor spreading was interrupted subsequently when the stresses were reversed

and convergence began between the Eurasian plate to the northeast and the African Arabian plate in the southwest.Thus, plate movements were divergent and then became merging.The subduction,i.e., The over advance of this Neo-Tethyan lithosphere on the Arabian continental margin was accompanied by overthrusting of the Hawasina and Sumeini nappes to form a tectonic pile on the edge of the Arabian Platform.The Samail Ophiolite is one of the major features of Oman Mountains.It extends from the south of the Musandam peninsula to the Batain Coast, south of Ras al Hadd.Structurally the Samail Ophiolite is the highest of the allochthonous units in the Oman Mountains.[1].It tectonically overlies the Metamorphic Sole, the Hawasina and Sumeini nappes.The Samail Ophiolite is subdivided into two major successions, the Mantle sequence and the Crustal sequence.The limit between these two sequences is the Moho.The mantle sequence consists of mylonitized beds of tectonized dunite and harzburgite,tectonized harzburgite, bands or lenses of discordant tectonized dunite in the hurzburgite and the Dunite bodies.The crustal sequences are largely comprised of undifferentiated dunite, Cumulate gabbro, laminated gabbro,sheeted dykes, lower basaltic pillow lavas and the sediments consisting of cherts and mud (black shale).

Most of the Chromite bodies in the Samail Ophiolite are located below the petrographic Moho, within the transition zone of mixed dunite and harzburgite near the top of the Mantle sequence. Only a few stratiform chromite deposits are reported in the basal part of the Crustal sequence. The Chromite being a minor constituent of ophiolitic rocks becomes concentrated to form economic accumulations, at places. Some models of chromite pods taking into account the mineralizing process have been developed. According to these models,the chromite has accumulated within cavities along magma dykes cross cutting the tectonized harzburgite. Chromite and olivine crystals in the rising convective basaltic melt to form chromite pods. The chromite accumulations thus formed in the uppermost of Mantle would later undergo deformation during plastic flow of the surrounding peridotites, provoked by the movements associated with oceanic accretion. They would then form drawn out lenses parallel to the foliation of the peridotite.In Oman,Chromite deposits are mainly of the concordant type.Nevertheless, some examples of the discordant type exit.The Chromite deposits vary greatly in shape.They may be tabular or lenticular,form dykes or veins, occur as pods or be disseminated, or form irregular patches.At places, low grade chromite for the extent of a few meters only is found.The geological map of the

Points UTM North UTM East

1 N 2564328 E 600456

2 N 2564223 E 600332

3 N 2564223 E 600456

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Concession area is shown in figure-3. Geological field studies carried out in and around the concession area reveal the presence of some interesting outcrops. At location, number 1 location (600442 easting and 2564375 northing), an outcrop is found exposed.The in-situ rock are largely comprised of ultramafic rocks consisting of dunite, harzburgite,serpentine,gabbro also intruding dunite in the transitional zone of mantle-crust.Layered igneous structures are These rocks host chromite in the reticular form.The mineralization of chromite in these rocks is concentrated within east-west trending zone. The rocks are generally fine to medium grained.At places; they become coarse grained also and show variation in colour from greenish, graying and brownish to blackish. The host rocks are cross cut by several vein generations composed mainly of serpentine group minerals, chlorite, and magnetite. High concentrations of magnetite are seen in some veins[7]. A brownish tint in the exposed section may be caused by alteration of serpentine to clay minerals. The occurrence at regular interval of a particular rock type showing pseudo-schistosity as a result of crystallization and deposition of platy minerals with their long axes parallel to the plane of layering is remarkable at places. This is generally a very thin litho-unit varying in thickness from a few centimeters to more than 25 centimeters. Between regular repetitions of such thin litho-unit, lenses of chromite bearing rocks are found. The maximum width of these lenses is at places 3 meters and the length 6 meters.These lenses have their long axes parallel to the trend of the layers. The striations on the slicken sided exposed surfaces, at places, are seen

well developed indicating some structural movement along the fault plane.

Following these rocks towards location number 2 (600465 easting and 2564119 northing),some change in the orientation of the chromite mineralization is noticed. Here the lenticular layered bodies are oriented in the north- south direction and its further extension can be traced in this direction.Here, the ultamafic association with gabbro and the process of serpentinization are pronounced. At location number 3 (600282 easting and 2564197 northing), harzburgite and dunite suits occupy most part of the ultramafic zone.They exhibit a dominant medium to coarse grained texture.This may be due to the corrosion and recrystallization of minerals resulting from the percolation of melts.At location number 4 (600333 easting and 2564371 northing),host rocks of ultramafic complex tend to be ferriferous. At places, these deep seated intrusive igneous rocks are found to contain chromite deposits.

III. METHODOLOGY

3.1 SAMPLE COLLECTION:

In total, 12 representative samples were collected during the field traverses in the concession area. The figure-4 shows sample location Map.

a) Geophysical survey b) Drilling and pit sampling

c) Sample analysis and determination of overall grade of the mineral.

d) Estimation of Reserves.

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b) Drilling and pit sampling: It is IT envisaged to drill at least 40 boreholes of 25 meters deep. Excavations of the few bits at the selected spots close to or on the exposed mineral body are carried out. The option for such activities is depending on the results of geological setting. Core samples described and preserved for each meter of drilling depth. Borehole logs and reports will be prepared for each borehole.Alternatively,pits are excavated in an appropriate number as required using rock breaking machines.The pit dimension will be of the order of 1x1x3(m).The rock element collected with variation in depth.A profile of mineral quality will be developed. Drilling and pit data are used to construct cross-sections for different parts of the concession area in order to estimate the available reserves. During the course of mining extension drilling programs will be undertaken to discover beyond 25 m depth.

c)Analysis of ore samples:The ore samples collected from the drilling of boreholes and excavation of pits and chemically analyzed.The origin and the methodological study of mineral identification same as adopted in a standard modern laboratory.The chemical observation and analysed finally the percentage of Cr2O3 and other related elements calculated.The presence of tracer elements in the mineral that may have an adverse impact will be confirm. The mineral constitution was confirmed together with the earlier results of the assay.

d)Reserve Estimation: Upon completion of the drilling program, the results are fully examined and cross-sections extended as appropriate to define the resource. Based on the topographical survey and geological cross profile of the resource was estimated. Results and all related supporting documents will be compiled in a report that will conclude the reserves available in metric ton.

IV. RESULTS AND DISCUSSIONS

Chromite is iron-black or brownish black in colour with brown streak, faint submetallic luster and uneven brittle fracture. It has hardness of 5.5 on Mohos scale. Its specific gravity varies from 4.5 to 4.8.It has the chemical composition of FeO.Cr2O3 and theoretically contains 68% Cr2O3 and 32% FeO.But,Al2O3,Fe2O3,MgO,CaO and SiO2 keep replacing some Cr2O3,thus reducing Cr2O3 content to as little as 28 per cent. Based on the chemical composition, the chromites are classified as high grade ore with high Cr2O3 and very low Al2O3 and Si2O3, ferriferous chromite with Fe2O3 more than 30%, aluminous chromite with Fe2O3 more than 20% and less than 30%,and siliceous chromite with high content of Si2O3.

While the Cr2O3 and Fe2O3 have reciprocal relationships, Al2O3 keeps varying from low percentage to as high as 18%. Two samples numbering as MC-1(Mubda chromite-1) and MC-2 from the area of study were chemically analysed.The assay results for sample number

MC-1 and sample number MC-2 are given in table-2 and table-3, subsequently.

Table-2. MC-1(Mubda chromite-1) (P=Phosphorus, S=Sulphur) Cr: Fe 1.9:1

The assay results from the two samples show Cr2O3 percentage 28.97 and 31.42, respectively.The Cr: Fe ratio for sample number MC-1 is 1.9:1, whereas for sample number MC-2, it is 2.1:1.The chemical analyses for both the aforesaid samples show aluminum percentage 15.49 and 16.43, respectively.Silica percentage and other impurities are also mentioned in the given assay results.

Thus, the chemical results reveal that the parent rocks exposed in the given area of study have a lower chromite content.The chromite deposits are generally located in dunite bodies of variable sizes and shape. They are large extent less common in contact with harzburgites.Their stratigraphic position is in the top part of the tectonized harzburgite, less than 1 km below the petrological Moho.

Considering various uses of chromate, this chromium may be exploited economically in manufacturing of chemicals and also using the higher grade of the available chromite for refractory purposes.The chromite is mainly used in metallurgical, refractory and chemical purposes. The metallurgical uses consist of a variety of alloys, mainly with iron, nickel and cobalt. Chromite is an important raw material for refractories that withstand temperatures about 2000 degree centigrade. Generally, refractory bricks are made by using chromite and magnesite.It is also used in manufacturing chemicals which in turn are used in pigment manufacture, leather and textile treatment, dying, leaching and oxidizing agents. The chromite flour is used in the glass, ceramic and brick industries as a natural colorant.

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2. The Chromite bearing rocks or accumulations are

exposed over a considerably large area

3. The assay results from the representative samples Show average Cr2O3 percentage of 30.195.in addition to the Total Chromite inferred reserve is estimated to be 50,000 ton of lower to medium

Grade. The area is found with generally lens shaped Deposits which are quantitative in size.

Table-3. MC-1(Mubda chromite-1)(P=Phosphorus, S=Sulphur),Cr:Fe 2.1:1

V. CONCLUSION AND

RECOMMENDATION

Based on the observation and fieldwork, interpretation of geophysical data and results of the chemical analyses of the surface samples, it is concluded that the entire area of concession is prospective and has the potential of economic interest for chromite trading.Based on the results of the first phase of exploration; it is recommended that the second phase of exploration should be taken up.Future exploration should map faults in detail, focusing on areas along the faults or between faults where grabens may have formed.It is recommended that geological mapping, geophysical observation and interpretation and water bore or well databases are integrated to prove depth of cover over the study area.

REFERENCES

[1] A1-Alawi,Z.,Gismelseed,A.M.,Yousif,A.A.,Worthing, M.A., Sutherland, H.H.,Rais, A.,Elzain, M.E.and Rawas A.D.Cation distribution in natural chromites from Oman.Science & Technology,1,55-61,1996.

[2] G.A..FatseasDormann, and H.Blanchard, Study of the Fe3+/Fe2+ratio in natural chromites (FexMgl_x)

(Crly~FeyAl~)O4.J.dePhys., 12,787-92,1976

[3]J.A.Lodya,,H.Pollack,,J.Nell,and A.Albers,Mrssbauer spectroscopy and magnetic susceptibility of natural chromites.Hyp.Int.,93,1789-94,1994

[4]S.MitraPal, and T.Pal, T.Petrogenetic implication of the Mrssbauer hyperfine parameters of Fe3+-chromites from Sukinda (India) ultramafites.Mineral.Mag. 55,535-42, 1991

[5] Murad,E. and Johnston,J.H.In Mossbauer Spectroscopy Applied to Inorganic Chemistry,Volume of natural chromite (Mg,FeII)(Al,FenIcr)zO4) samples from the Bushveld Complex, South Africa.Hyp.Int., 84,427-31,1987 [6]Robins,M., Wertheim,G.K., Sherwood,R.C. and Buchanan, D.N.E. Magnetic properties and site

distributions in the system FeCr2Oa_Fe304_(Fe2+Cr2_xFe3x§ J.Phys. Chem. Solids,

32,717-29, 1971

[7]Tj.Peters,J.D.Kramers Chromite deposits in the ophiolite complex of Northern Oman Mineralium Deposita Vol. 9, Issue 3, pp 253-259, September 1974.

SPECIFICATIONS RESULTS (PCT)

Cr2O3 31.42

MgO 21.51

Al2O3 16.43

SiO2 10.47

P <0.02