Mineral Industry in Egypt– Part II Non-Metallic Commodities – Silica Ores

Journal of Mining World Express (MWE) Volume 5, 2016 www.mwe‐journal.org

doi: 10.14355/mwe.2016.05.002

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Mineral Industry in Egypt– Part II

Non‐Metallic Commodities – Silica Ores Ezz‐El Din, M.1; Abouzeid, A. M.2; El maadawy, Kh .3; Khalid, A.M.4; and El Sherif ., R.E.5

1‐Egyptian Mineral Resource Authority EMRA

2‐ Cairo University, Faculty of Engineering, Dept. of Mining.

3‐ Minofiya University, Faculty of Sciences, Drpt. Of Geology.

4‐Ex‐Egyptian Mineral Resource Authority EMRA

5‐Geologist free hand

Abstract

Silicon, nowadays, is involved in many advanced and high technology industries due to its unique property. The silica ores

exist in the form of quartz, quartzite, and white sand. In Egypt, quartz is confined to igneous and metamorphic origins, while

white sand exists in the form of sedimentary deposits. Quartz and quartzite are found in association with basement rocks in

Eastern Desert and Western Desert. While white sand deposits are widely distributed in Sinai, Eastern Desert, and Western

Desert, with the most commercial deposits in Sinai and Eastern Desert.

Estimation of the geological and economic reserves indicate huge tonnages of all types of silica ores. Quartz reserves sum up to

20 million tons, and silica sands sum up to more than 3 billion tons. Evaluation of the chemical and physical characteristics of

the silica in Egypt showed high quality silica with low contaminations. The major part of these reserves is available through

open‐pit mining with very low costs due to minimal overburden. Some of the silica sand deposits contain a high percentage of

white kaolin, up to about 11 percent, which is separated as a valuable economic byproduct. The basic processing operations of

the white sand are washing, screening, attrition scrubbing, desliming and dewatering. In some locations magnetic separation is

used for the removal of magnetic impurities. Academic research work showed that the quality of the white sand product can be

improved when froth flotation operation is used.

Keywords

Silica Ores in Egypt, Quartz, Quartzite, Glass Sands, Processing of White Sands

Introduction

The silica occurrences encompass basically quartz, quartzite and white sand. Silica, nowadays, is essential in high

technology industries due to its ability to act as metallic and/or non‐metallic substance. Its unique property makes

it one of the most useful natural substances. It is composed of silicon and oxygen, the two most abundant elements

in the Earth’s crust, in the form of SiO2. It is composed of silica tetrahedral, and belongs to the rhombohedral

crystal type, hexagonal system. The silicon element represents 28.1% of the constituents of the Earth’s crust (Wills,

2006). Silica occurs mostly in a crystalline form and rarely as a non‐crystalline (amorphous) form. In its pure form,

it is a colorless, odorless, non‐combustible solid. Crystalline silica has three main crystalline varieties: quartz (by far

the most abundant species), tridymite, and cristobalite. The world annual production of silica in 2013 is more than

140 billion tons of industrial silica sands (Dolley, 2013). Figure 1 presents the world production of silica in the

period 2007 – 2013. The world production rate ranged from 118 million tons in 2009 to 142 million tons in 2013.

Silica ores occur in two forms quartz and white sand. They differ mainly in the origin where quartz is present in

igneous rocks as a residual of magmatic activities or hydrothermal solutions, and metamorphic rocks, while white

sand is a weathered product of old sedimentary, metamorphic, or igneous origin.

Due to this origin white sand could be contaminated with clay minerals in different ratios. As a matter of fact, the

strategic importance of silica sands attracted many scientists around the world to investigate the origin of the silica

ore deposits, characterize them, and work for improving their grade in practical and economic manners ( Abdallah

et al., 1992; Awadh, 2010; Bandel et al., 1987; Blatt et al., 1980; Carver, 1971; El‐Bokl et al., 1993; Ezz El Din, 2007;

Issawi et al., 1999; Khalid, 1993; Klitzsch et al., 1990; Madanat et al., 2006; Norton, 1957; Mustafa et al., 2011;

www.mwe‐journal.org Journal of Mining World Express (MWE) Volume 5, 2016

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Ramadan, 2014; Sundararajan et al., 2009; Krinsley and Boornkamp, 1973). The natural silica cycle and sand texture

are shown in Figures 2 and 3 (Barrett and Beskeen, 1986). White quartz sand, as defined by the British Geological

Survey is “sand used for applications other than construction aggregates and which are valued for their physical

and chemical properties” (Platias et al., 2014).

FIGURE 1: WORLD PRODUCTION OF SILICA IN THE PERIOD 2009 T‐ 2013 (DOLLEY, 2010, 2011, 2012, 2013)

FIGURE 2: NATURAL CYCLE OF SILICA FIGURE 3: CYCLE OF FORMATION OF

(QUARTZ AND SILICA SAND) FORMATIONS ROUNDED SAND FROM MOTHER ROCK.

(BARRETT AND BESKEEN, 1986). (BARRETT AND BESKEEN, 1986).

Silica sand is a weathered derivative of quartz, as seen in Figure 3. It occurs as loose sand (sand dunes) and/or as

consolidated rock, as seen in Figures 4 and 5. Sand dunes are formed by moving wind, flowing water, or glaciers.

The grain size ranges and size distributions of the silica sands depend on the mode of formation. The desert sand is

very closely sized, whereas the glacial sand is very coarse and has a wide size distribution. The mode of formation

affects greatly the size distribution of the sand. Figure 6 shows the different distributions according to the process it

was formed with (Barrett and Beskeen, 1986).


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Uses of Quartz and Silica Sand

Electronic‐grade quartz crystal is single crystal silica with properties that make it uniquely useful in accurate filters,

frequency controls, and timers used in electronic circuits. These devices are used for a variety of electronic

applications in aerospace hardware, commercial and military navigational instruments, communications

equipment, computers, and consumer goods. Such high technology uses generate practically all the demand for

electronic‐grade quartz crystals. A lesser amount of optical‐grade quartz crystal is used for lenses and windows in

specialized devices. Natural electronic‐grade quartz crystal has been replaced by cultured quartz crystal since 1971.

The use of natural crystal for carving and other gemstone applications is still going on (Dolley, 2004).

Silica sands are used in many commercial processes and products, and therefore, are commonly classified on the

bases of their industrial applications. This classification depends on the mineralogical, chemical, and physical

properties such as size, size distribution, surface area, melting point, and particle shape (Platias et al., 2014). In

general, the specifications of the silica sand depend on the intended use and the purity level of the quartz sand.

Figure 7 shows the distribution of the uses of white silica sand in the world in 2013 (Zarad, 2014).

FIGURE 4: CONSOLIDATED SILICA SAND.

FIGURE 5: WHITE SILICA SAND DUNES.


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FIGURE 6: THE DIFFERENT MODES OF SAND FORMATION: A) DESERT SAND, B) BEACH SAND, C) LAKE CLAY, D) GLACIAL

WASHOUT (BARRETT AND BESKEEN, 1986).

Silica sand is used mainly for making glass (optical glasses such as cameras, optical instruments, microscopes, in

optical fibers, and other types of glass). For this purpose, the British Standard BS2975 includes recommended limits

for the composition of quartz sand for seven different grades of glass, as seen in Table 1. Industrial silica sands are

also used for abrasives, grouts, and extenders. Here, particle size and surface area of the quartz sand are two of the

most important attributes. Quartz sand is also used to make moulds and cores for metal castings. This use requires

sand consisting of uniform‐sized rounded grains of quartz (Platias et al., 2014; Moldenke, 1930). There are many

other uses of silica sand such as electronics, renewable energy sources (solar energy), the manufacture of silicon

carbide, sodium silicate, Portland cement, silicon alloys with metals, silicon metal (chips and wafers), filter media

in water treatment, hydraulic fracturing in oil reservoirs, sand blasting, rubber, paints, plastics, polymers, and a

host of other applications (Platias et al., 2014; Sundararajan et al., 2009). Table 2 summarizes the chemical

composition limits of the silica sand for various products as specified by the American Ceramics Society and

National Bureau of Standards for different glass products (Norton, 1957). Since size distribution of glass sands is an

essential attribute for the glass raw materials, Table 3 provides the size ranges of the sand as recommended by both

the American and British standards. Table 4 summarizes the required chemical compositions of quartz

recommended for various industries.

TABLE 1: BS2975 SPECS FOR THE GRADES OF SILICA SAND FOR THE DIFFERENT TYPES OF GLASS PRODUCTS (BRITISH STANDARD INSTITUTION, 1988).

Grade Product Composition

SiO2 % Fe2 O3 % Al2 O3 % Cr2O3 %

A Optical glass 99.7 0.013 o.2 0.00015

B Tableware glass 99.6 0.01 0.2 0.0002

C Borosilicate glass 99.6 0.01 0.2 0.0002

D Colorless container glass 98.8 0.03 0.1 0.0005

E Flat glass 99.0 0.1 0.5 ‐

F Colored container glass 97.0 0.25 0.1 ‐

G Insulating fibers 94.5 0.3 3.0 ‐


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TABLE.2: RECOMMENDED SPECIFICATIONS PROPOSED BY THE AMERICAN CERAMIC SOCIETY AND NATIONAL BUREAU

OF STANDARDS FOR CHEMICAL COMPOSITION OF GLASS SAND USED FOR THE PRODUCTION OF DIFFERENT GLASS PRODUCTS (NORTON, 1957).

S/N Product/glass Min. SiO2% Max. Al2O3% Max. Fe2O3% Max. CaO+MgO %

1 Quality optical glass 99.8 0.1 0.02 0.1

2 Quality flint containers

& table ware 98.5 0.5 0.035 0.2

3 Quality flint glass 95 4 0.035 0.5

4 Quality sheet & plate

glass 98 0.5 0.06 0.5

5 Quality sheet & plate

glass 95 4 0.06 0.5

6 Quality green container

& window glass 98 0.5 0.3 0.5

7 Quality green glass 95 4 0.3 0.5

8 Quality Amber glass

container 98.5 0.5 1.0 0.5

9 Quality Amber 95 4.0 10 0.5

Pure white sands are used mainly in glass making, silicon chips and wafers, glass fibers, and other industries

(Arrifin, 2004). Figure 7 shows that the main uses of silica sands worldwide are distributed as follows: 62% for

making glass, 14% for silicon chips, 6% for glass fibers, and 18% for other purposes (Zarad, 2006).

TABLE 3: GRADING OF SILICA SANDS FOR GLASS MANUFACTURE AS SPECIFIED BY THE AMERICAN AND BRITISH STANDARDS.

Particle Size, microns Weight, percent

+ 1000 0.0

‐1000 + 600 2 to 6

‐600 + 420 10 to15

‐420 + 150 80 Minimum

‐150 + 125 10 Maximum

‐125 5 Maximum

TABLE 4: RANGE OF THE CHEMICAL COMPOSITIONS OF QUARTZ REQUIRED FOR DIFFERENT INDUSTRIES.

Industry SiO2 , % Al2O3 , % Fe, % CaO, % Na2O, %

Military production 93‐ 96 0.25 1.5 ‐ ‐ ‐

Electric poles 96‐ 99.5 ‐ 0.5 ‐ ‐

Ceramics 97.7‐ 99.5 0.02 0.01‐ 0.19 0.01‐0.05

Ferro‐silicon 98 ‐ 99 0.2 0.26 0.02 0.2 ‐

Chemicals 96 0.4 ‐ ‐ ‐

Silicon carbide 99.5‐ 99.75 ‐ 0.04 0.01 0.01

Optical and crystals 99.7‐ 99.8 0.01 0.014 0.02 ‐

Silica glass (sodium silicate) 99 0.075 0.92 ‐ ‐

Space industries 99.9 ‐0.02 0.01 0.01 ‐

Foundry 72.5‐ 91.11 0.08 1.0 6.2‐ 24.7 ‐ ‐

Rubber 98 ‐ 0.1 ‐ ‐

Bricks 95 ‐ 99 0.1 2.8 0.3 ‐ 1.3 0.2 2.4 0.2 1.5

To meet the required specifications for a specific product, the sand often has to be subjected to extensive physical

and chemical processing. This involves crushing, screening and further adjusting the grain‐size distribution,

together with removing the contaminated impurities in the sand bulk and from the surface of the individual sand

grains. Presence of metallic oxides in the glassmaking sands usually produces colored glass. If iron is present, the

resulting glass is colored green or brown. The iron level is consequently the most critical parameter in determining

whether particular sand can be used to make clear glass. Sands used to manufacture colorless glass are therefore

likely to be processed further by certain methods such as gravity separation, magnetic separation, acid leaching, or


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even froth flotation. Figure 8 presents the general layout for extracting and processing of white sand for the

different industrial uses (BGS, 2009).

FIGURE 7: DISTRIBUTION OF THE WORLD USES OF WHITE SILICA SANDS (ZARAD, 2014)

FIGURE 8: GENERAL LAYOUT OF QUARTZ SAND PROCESSING (BGS, 2009)

Quartz, Quarzite, and Silica Sands in Egypt

Quartz and Quartzite

Quartz generally occurs in Egypt in the Eastern Desert in association with igneous and metamorphic rocks, while

quartzite is commonly found in the Western Desert (Omayra, 2002). In the following, the distribution of each type

and possible reserves and chemical compositions are given.

1) Mode of Quartz Occurrences

Quartz occurs in nature in many forms, but the commercial quantities generally crops out in the following

forms:

1‐Quartz caps of plutons are formed as a result of magmatic differentiation and after granitic pluton cooled and

solidified. Some remaining magma gets more concentration in water and silica which accumulate at the roof of

granitic bodies or associate with pegmatites. These quartz caps differ in size and purity from one place to the

other. The main gangue minerals are mica and rarely feldspars, as seen in Figure 9 (Ezz El Din, 2007).

2‐Quartz veins: the quart which was formed as caps leaves residual solutions that penetrated through the cracks

and along fissures to form veins, and sometimes form lensoidal bodies with different dimensions. Figures 10 ‐13

show some quarts bodies in the Eastern Desert.


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FIGURE 9: MARWA SEWEQAT QUARTZ (EZZ EL DIN, 2007)

FIGURE 10 SHOWS QUARTZ OVER GRANITOID ROCKS; (A) A PHOTOGRAPH SHOWING TRACHYTIC DYKE CUTTING THROUGH

THE BASIC DYKE, WHICH CUTS BOTH QUARTZ AND FOLIATED TONALITE AT WADI FANAT, AND (B) A PHOTOGRAPH

SHOWING A BASIC DYKE CUTTING A FOLIATED TONALITE AT WADI FANAT BOTH PHOTOS A AND B ARE TAKEN LOOKING

WEST (EZZ EL DIN, 2007).

FIGURE 11: WADI MUBARK QUARTZ (EZZ EL DIN, 2007)

FIGURE 12: QUARTZ PLUG OF WADI UMM JURUF (LOOKING NORTH) (EZZ EL DIN, 2007).


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FIGURE 13: ABU FANANI QUARTZ (EZZ EL DIN, 2007)

3‐Quartzite is present in both sedimentary and metamorphic rocks. It is originated from the metamorphism of

sandstone and, generally, form sheets and lenses. Quartzite in Aluwaynat area South West of Egypt form large

extended sheets occasionally associated with mica and feldspars (Naim et 1998; Khalid et al.2002; Khattab et al

2002). Table 5 and Figure 14 show the locations of the most important quartz deposits in Egypt.

The annual production and export quantities of quartz are shown in Figure 15. The production is relatively

more than the exported amount, because the difference is used locally. The production of the quartz has

significantly decreased in the year 2012/2013 as a result of temporally local reasons.

TABLE 5: LOCATIONS AND GEOLOGICAL RESERVES OF QUARTZ IN EGYPT

Location Reserves, 103 tons

Composition

SiO2, % Fe2O3 , % Al2O3 , %

Abu‐Fanani 100 96.4 0.17 0.27

Um Ghanam 40 ND ND ND

Rod Ashab ND ND ND ND

Hamri 15 98.52 0.19 0.2

Um Rashed 40 ND ND ND

Gabal El‐Taweela 20 ND ND ND

Sweiget El‐Beda 500 97.93 0.33 0.25

Wadi Essel ND ND ND ND

Wadi Abu‐Shabah, Qussier area 130 99.28 0.04 0.15

Um Esh El‐Hamra, Fawakheir 4,340 99.01 0.24 0.04

Wadi Karim, Bir Karim 7,456 98.28 0).29 0.17

Hamra Dome 1,354 99.34 0.12 0.02

Wadi Atalla 269 ND ND ND

Gabal Shayiab 250 99.6 0.19 0.02

Wadi Fanat 800 99.45 0.14 0.02

Wadi Warbeit 1 405 99.22 0.27 0.03

Wadi Warbeit 2 81 99.44 0.28 0.02

Wadi Boyia 697 99.09 ND 0.06

South Soruk A 211 98.74 ND 0.06

South Soruk B 26 98.98 ND 0.06

Mansour Diab A 1,325 ND ND D ND

Marwat Klimkan‐W. El Beida 10,000 ND ND ND

W. Anter‐Road Abid 400 ND ND ND


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W. Khedah‐G.Um Athli 450 ND ND ND

G. Sorasr 35 ND ND ND

W. Kharit 1,300 ND ND ND

G. El Nikhairah 50 ND ND ND

G. Humr Al Karim 130 ND ND ND

W. El Gararah 2,300 ND ND ND

G. El Kahfa 940 ND ND ND

FIGURE 14: MAP OF EGYPT SHOWING THE QUARTZ OCCURRENCES IN THE EASTERN DESERT, ASSOCIATED WITH THE RED

SEA GEOLOGICAL STRUCTURE.

FIGURE 15: PRODUCTION AND EXPORT OF QUARTZ IN EGYPT IN THE PERIOD 2010 / 2013 (ZARAD, 2014)


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White Sand (Glass Sand)

Silica sands are the most widely used among all the non‐metallic commodities for their physical and chemical

characteristics such as color, hardness, heat resistance, high melting point (1760ºC) as well as their low price.

Geologically, white sands in many places around the world are formed in the Paleozoic Formation.

The important locations of white sands in Egypt are widely distributed in Sinai, Northern part of Eastern Desert,

and in the Western Desert. For the last few decades, the Egyptian glass and crystal factories have been using the

white sand for their first‐class international products. The demand for this high purity sand is continually

increasing (Kamel et al., 1997). The high quality and the potential value of the Egyptian white sands (silica sand

deposits) attracted the attention of many researchers (Khalid, 1993; El‐Bokle and Hasanein, 1993; El‐Fawal, 1994;

Fathi, 2002; Bayat et al., 2007; Mustafa et al., 2011; and Ramadan, 2014; Weissbrod, 2004). About 16 localities

containing high‐grade silica sands have been identified in Egypt. The most important of these are Wadi Qena and

Wadi El‐Dakhl (El‐Zaafarana) located in the Northern part of the Eastern Desert and El‐ Maadi, and Gebel El‐

Gunnah in Sinai, as seen in Figure 16 (El‐Wekeil and Gaafar, 2014). The reserves at the mentioned areas exceed 3

billions of tons of the high quality silica sand, which fulfill the specifications of the glass industry, paints, foundry,

chemicals, and ceramics raw materials.

FIGURE 16: LOCATION MAP OF GLASS SANDS IN THE MAIN OCCURRENCES OF EGYPT (EL‐ WEKEIL AND GAAFAR, 2014).

2) Geology

1‐Eastern Desert:

The largest deposit of white sand in the Eastern Desert lies at Wadi Qena. The white sand in Wadi Qena

constitutes most of the lower Paleozoic Naqus Formation (450 km2) North‐East of Qena. The Northern part of

Wadi Qena consists of the exposed lower Paleozoic rock units which are represented by Araba and Naqus

Formation (Wanas 2011). The Naqus Formation rests unconformably on the peneplained Precambrian

crystalline rocks of Araba‐Nubian shield and form scattered outcrops in a series of hills and mesas. The

thickness of the Naqus Formation ranges from 22m to 120 m (Abou El‐Anwar and El‐Wekeil, 2013).

Two stratigraphic sections have been investigated in the study area by Abou El‐Anwar and El‐Wekeil, 2013.


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These sections comprise a major part of the Naqus Formation (Figure 17). The first section (A) is about106 m

thick and the second section (B) measures around 120 m. The Naqus sandstones have a similar lithological

characteristic in both sections. They are commonly, white, fine‐to‐medium grained, moderate‐to‐well‐sorted,

subangular to subrounded, consolidated to loosely consolidated materials, and occasionally contain coarse sand

and granules. The sandstones are characterized by the presence of different primary sedimentary structures

such as planar‐ and trough cross‐bedding and flat bedding. Kaolinitic lenses are randomly distributed

throughout the whole sequence especially at the upper part of the sediment. The upper boundary of the Naqus

sandstones is absent in section (A), while section (B) is unconformably overlain by the shallow marine

sediments of the Cenomanian Galala Formation. The later formation is made up of about 15 m thick greenish

yellow shale and sandy marl intercalated with claystone.

FIGURE 17: LITHOSTRATIGRAPHIC COLUMNAR SECTIONS OF THE MEASURED NAQUS SANDSTONE SEQUENCES MODIFIED

AFTER (ABOU EL‐ ANWAR AND EL‐ WEKEIL, 2013).

2‐ Sinai

The white sand deposits in Sinai belong to the Naqus Formation of Early Paleozoic age. The Early Paleozoic

section in Abu Durba in Sinai was classified, from base to top, as Araba Formation and Naqus Formation (Early

Paleozoic age), unconformably overlain by Malha Formation of Lower Cretaceous (Hassan,1967; Said,1971;

Omara, 1972; Issawi and Jux, 1982). The term Naqus Formation was introduced by Hassan (1967) and was

adopted by Said (1971) describing a thick siliciclastic sequence. It unconformably overlies the Araba Formation

and is overlained unconformably by the Malha Formation.

Naqus Formation at the Saint Katherine‐Newbie consists mainly of a thick sandstone sequence measuring about

200m thick (Figure 18). Generally, the lower 30 m are white massive sandstone beds with minor ferruginous

clayey and kaolinitic interbeds. The rest of the sequence is formed of cross‐bedded and varicolored sandstone

ranging in color from white to pale brownish and contains abundant quartz pebbles (Figure 18). It is almost

devoid of organic remnants. Termites (Awadh, 2010) could borrow and penetrate the sand glass giving the

appearance which is called Mashrabia or Fenestra structure (Abdel‐Rahman, 2002) as shown in Figure 19. Fathi

2002 studied the physical and chemical characteristics of silica sand deposits of Wadi Watir Sinai and came to

the conclusion that it is suitable for art and domestic glass manufacture with simple screening for the removal

of coarse and fine fractions.


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FIGURE 18: COMPOSITE LITHOSTRATIGRAPHIC COLUMNAR SECTION OF NAQUS FORMATION IN SAINT KATHERINE‐NEWBIE

AREA (ABDEL RAHMAN, 2002).

FIGURE 19: NAQUS FORMATION AT SAINT KATHERINE‐NEWBIE AREA SHOWING MASHRABIA (FENESTRA) STRUCTURE.

ARROWS POINT TO THE REMNANTS OF TERMITE TRENCHES (RAMADAN 2014).


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TABLE 6: LOCATIONS AND SPECIFICATIONS OF THE MOST IMPORTANT WHITE SAND DEPOSITS IN EGYPT.

Location Reserves,

M ton SiO2, % Fe2 O3, % Al2 O3, % CaO+MgO, %

Western Desert

Wadi El‐Natron 1.7 92.4‐95.4 0.3‐0.54 1.24‐2.6 1.4‐2.1

New Valley 1 ND 93.9‐96.0 0.28‐1.02 0.01‐2.01 0.6‐1.2

New Valley 2 ND 93.9‐96.1 0.30‐1.3 0.01‐2.1 0.8‐1.2

North Fayoum Unlimited 90.5‐98.0 0.25‐2.24 0.03‐2.24 0.71

Eastern Desert0.86

Wadi Qena 258 94.8 0.33 4.0 ‐

Wadi El‐Dakhl 10 98.5‐99.6 0.01‐0.02 0.036‐0.19 0.03‐0.2

East Edfu Unlimited ND ND ND ND

East Maadi Medium 95.0‐97.0 0.27‐0.42 0.6‐1.44 0.12‐0.2

Sinai

Abu El‐Darag 4.1 97.2‐98.6 0.03‐0.07 0.23‐1.43 0.22‐1.07

Gabal El‐ Menshereh 3 98.1 0.08‐0.093 0.026‐0.32 0.06‐0.28

Wadi Filly 1.3 91.4‐99.6 0.027‐0.26 0.016‐0.37 0.1‐1.23

Abu Zneima 1.25 97.5‐99.7 0.01‐1.34 0.21‐1.35 0.004‐0.2

El‐Gunna 2,500 90.3‐96.5 0.026‐0.08 1.85‐6.0 0.01‐0.35

Wadi Watir ND ND ND ND ND

Kathrine‐ Newbie Road ND ND ND ND ND

Ramadan (2014) studied the Physicochemical properties of the white sandstone deposits along the Nuweiba‐

Saint Katherine road, in Southern Sinai region for probable utilization in industrial applications such as solar

cells, sheet glass, and oil production processes. In his study, Ramadan found that the physical characteristics of

these sands are fine to medium in size, well‐sorted, and about 90% of the grains fall in the range of 1.0 mm to

0.125 mm. Mineralogically, the sandstones are quartz arenite (more than 85%). Chemically, the ranges of

compositions are: from 0.55‐1.67%, Al2 O3, from 0.41‐1.66% Fe2 O3, and from 91.17‐95.99% SiO2. The author came

to the conclusion that the white sand deposits of Nuweiba‐Saint Katherine region shows that they are of well‐

sorted grain sizes, considerable purity, with quality ranges compatible with grades (E,F and G) on the British

Standard (Table 1), and Serial Numbers (S/N) 7 to 9 according to U.S specifications (Table 2).

The production and exported glass sands in the period 2010 to 2013 are shown in Figure 20. It is clear that most

of the produced white sand was exported in the year 2010/2011, whereas in the period 2011/2013, both the

produced and exported glass sands were significantly lower than before. This trend is probably due to local

reasons.

FIGURE 20: THE RATE OF PRODUCTION AND EXPORT OF THE WHITE SANDS IN EGYPT IN THE PERIOD 2010 TO 2013 (ZARAD,

2014).


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For economic reasons, more than 80% of the exported white sand is sold to Mediterranean and Middle East

countries. This is mainly due to the easy transportation by sea at low cost. This is understandable because the

price of the sand is relatively low. Figure 21 shows the main importing countries for the white sand from Egypt,

and the percentages imported by each country. The countries importing the Egyptian white sand in the year

2012/2013, arranged in a descending order, are Turkey (32 %), Lebanon (22.8 %), Italy (9.3 %), UAE (8.9 %), and

Greece (6.7 %).

FIGURE 21: THE MAIN COUNTRIES IMPORTED THE EGYPTIAN WHITE SANDS IN THE YEAR 2012/2014 (ZARAD, 2014).

To meet the tight specifications of silica sands, the sand often has to be subjected to extensive physical and

chemical processing. This involves crushing, screening and further adjusting the grain‐size distribution,

together with removing the contaminating impurities in the bulk and from the surface of the individual quartz

grains. Sands used for manufacturing colorless glass are therefore likely to be processed further by certain

methods such as acid leaching, magnetic separation, froth flotation, and/or gravity separation.

3) Mining

Mining methods of industrial sands depend on the type of sand deposit. Unconsolidated deposits are mined

using front‐end loaders, scrapers, or bulldozers. Material is dug, excavated, and then loaded onto trucks to

stockpiles or to the processing plant. Other unconsolidated deposits are mined with dredges or draglines. A

hydraulic dredge uses a suction pipe to excavate the sand, which is pumped to surge piles or directly to the

plant. Loosely consolidated material can be mined using a high‐pressure hydraulic monitor. Sand washed from

the working face is collected in a sump, and then pumped to a dewatering/surge pile, and sent to the plant. In

the case of well‐consolidated deposits, conventional drill‐and‐blast methods are used, where the sandstone is

“mucked”, haul, and transported to the crushing section of the processing plant. Due to the low price of the

sand, underground mining may only be used for extracting competent, well‐lithified sandstone or quartzite by

using conventional drill‐and‐blast methods, the material is then hauled or conveyed to the processing plant or

surge piles (Kogel et al., 2006).

In Egypt, surface mining is usually used for mining of silica sands as a result of the presence of little or no

overburden, about 1‐15 m, in almost all the white sand deposits. The ore is drilled and blasted using Anfo and

gelatin in the ratio of 3:1. The boreholes are drilled using pits of 3 inch diameter to a depth of 10‐12 meters,

filled with explosive mixture, stamped. About 100 bore holes are designed in a specific pattern, tied together

with craftin, and detonated with a detonating capsule. The broken rock is transported to a size reduction and

screening section, to be prepared for washing and processing (Zarad, 2014).

4) Processing

The type of processing or beneficiation of silica sand is directly related to the relative nature of the sand deposit

and the purity of the required product. Regardless of markets, sands are, at a minimum, washed, dried, and

screened. A typical processing circuit would include washing to remove clays and other deleterious material.

Some processes may require that the material report to a rod or a ball mill for wet grinding. The slurry from the

wash‐and‐mill circuit is pumped to a desliming circuit in which hydrocyclones remove the slimes. The washed

sand is then subjected to a coarse separation cut by hydrosizing or wet screening. The sand is further dewatered


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by reporting to surge piles or cyclones. Once the sand contains approximately 70% solids, it reports to attrition

scrubbing in tanks equipped with propeller‐type blades. In some cases, the water is acidified with an inorganic

acid. Attrition scrubbing removes clays, iron oxides, and other materials that may be on the surface of the sand

grains. In addition, attrition scrubbing creates a fresh surface on the quartz and non‐quartz minerals to enhance

reagent attachment, if flotation is to be used. Flotation, cationic or anionic, is used only when high‐purity quartz

is required for the market (Bayat et al., 2007). Once washing and flotation (if required) is completed, the sand is

dried to meet the market specifications (Kogel et al., 20106; Sundararajan et al., 2009; Al‐Maghrabi, 2004). Table

7 presents the iron oxide content in silica sand Grade I from Europe and USA when purified using gravity and

magnetic separation techniques (GWP Consultants LLP, 2010).

For the Egyptian white sands, usually, processing does not require complicated flow‐sheets. Basically only

washing and screening are carried out to remove coarse and fine fractions. For high purity sands, attrition

scrubbing with acidified water removes adhered fine clays and iron stains. For the removal of heavy minerals,

low or high intensity magnetic separation, dry or wet, and /or flotation may be used (Zarad, 2014). For the

separation of kaolin as a byproduct in some ores, hydrocyclons are used efficiently to give a coarse sand

product and a fine kaolin product. However, because flotation is an expensive process, its use will depend on

the payback from the purified product.

TABLE 7: TYPICAL RESULTS OF THE GRAVITY AND MAGNETIC SEPARATION ON SILICA SANDS FROM EUROPE AND USA.

Stage of processing Silica Sand I (Europe) Silica Sand I (USA)

Feed, Fe2 O3 % 0.085 0.089

Gravity spirals 1 pass, Fe2 O3 % 0.038 0.066

Gravity spirals 2 passes, Fe2 O3 % 0.033 0.049

Magnetic separation at least 2 passes, Fe2 O3 % 0.014 0.039

Some Academic research work was carried out to purify the Egyptian white sands. El‐Wekeil and Gaafar (2014)

beneficiated silica sand from El‐Naqus formation in Wadi Qena, Eastern Desert. They used attrition scrubbing

to loosen sands from kaolin and clean the sand surface from the contaminating elements such as iron,

chromium, and titanium using water acidified with 10 % HCl. The attritted sample was screened to remove

coarse grits (+2.0 mm). The ‐2 mm material was subjected to classification using different hydrocyclones to

separate the feed into coarse sand product, sand‐kaolin product, and white kaolin product. For the fine fraction,

the authors used a magnetic filter to remove magnetic and paramagnetic contaminants. For cleaning the coarse

product, they used induced roll magnetic separator and Wilfley table to remove heavy minerals. They obtained

quartz sand product containing 98.6 % SiO2 with less than 0.025 % Fe2 O3 and less than 0.045 % TiO2 after

attrition scrubbing and the first stage of hydrocycloning. In the second and third stages of hydrocycloning, they

obtained white kaolin containing 46.6 % silica and 37.1 % Al2 O3 representing about 11 % of the total feed. They

also cleaned two size fractions of the sand: a fine fraction, 0.25 ‐0.125 mm, and a very fine fraction, 0.125‐0.063

mm. These fractions were treated by attrition scrubbing using acidified water containing 10 % HCl. The

scrubbed material was deslimed, washed and dried. The dried material was subjected to sink‐float test using

bromoform liquid (sp. gr. 2.85), where the sink fraction was collected, washed, dried and weighed. The float

fractions were collected, washed, dried, and passed through a magnetic filter to remove the coloring

contaminants. Abou El‐Anwar (2007) showed that the beneficiation of El‐Masaid silica sands, West of El‐ Arish,

Sinai can be done by washing with sea water followed by fresh water. The sand is then treated with acidified

water containing 10 % HF or 10 % HCl at room temperature for long time. He reported that this sand can be

further purified by flotation to remove the deteriorating material such as iron, manganese and heavy minerals.

He also stated that washing the sand with water containing 10 % HCl prior to flotation improved the product.

Hagras (2013) showed that gravity separation is suitable for purifying silica sands as a result of the removal of

heavy minerals. Ibrahim et al. 2013) purified a white sand sample from Abu Zeneima area, Sinai. The original

sample contained 99.44 SiO2, 0.046 % Fe2 O3, 0.044 % Al2 O3 , 0.03 % TiO2, 0.11 % MnO, and 0.02 MgO. By dry

screening, they removed the +0.6 mm and the ‐0.106 mm fractions. The sized fraction was subjected to attrition

scrubbing, deslimed and washed with water. The attritted material was treated on Wilfley table. The authors

reported that screening the sample reduced the iron oxide content down to 0.04 %, attrition scrubbing and


24

desliming reduced the iron oxide content to 0.025 %, and tabling reduced it to 0.02%. The final sand product

contained 0.018 % Fe2 O3 and 0.09 % Al2 O3. Of course the authors did not report the SiO2 percent in the final

product, because it will not differ much from its percentage in the feed.

Summary

White sands in all its forms: quartz, sandstone, and silica sand are essential commodities for various high

technology industries. Electronic‐grade quartz is used in accurate filters, frequency controls, and timers in

electronic circuits. These devices are used for a variety of electronic applications in aerospace hardware, military

navigation instruments, communications equipment, and computers.

White sand is the final product of rock weathering of any quartz‐bearing rock which creates sand: igneous,

sedimentary, or metamorphic (Shaffer, 2006). It is called industrial silica sand, and defined by the BGS as “sand

used for applications other than construction aggregates and which are valued for their physical and chemical

properties.” It is used for glassmaking, water filtration, foundry industries, manufacture of electronic chips and

wafers, grouts, paints, and fillers for plastics, polymers, rubber and other applications.

In Egypt, there are a large number of high‐quality quartz deposits. All of them are spread in the Eastern Desert

along the Red Sea Coast. Their modes of occurrence are as quartz caps of plutons formed as a result of magmatic

differentiation and after granitic pluton cooled and solidified. Quartz veins were formed from the residual

solutions after forming the caps, and these solutions penetrated through the cracks and along fissures to form veins

and/or lensoidal bodies. Quartzite is present in both sedimentary and metamorphic rocks. It is originated from the

metamorphism of sandstone. The quarts reserves in Egypt exceed 20 million tons in more than 30 localities.

The white sands in Egypt exist in Sinai, North part of Eastern Desert, and in the Western Desert. The most

important sandstone deposits in Egypt, quantity and quality, are in Wadi Qena in the Eastern Desert and Gebel El‐

Gunna in Sinai. The white sand in Wadi Qena constitutes most of the early lower Paleozoic Naqus Formation,

North‐East of Qena. The Northern part of Wadi Qena consists of the exposed lower Paleozoic rock units which are

represented by Araba and Naqus Formation. At the Saint Katherine‐Neuwiba, the Naqus Formation consists

mainly of a thick sandstone sequence. Generally, the lower 30 m are white massive sandstone beds with minor

ferruginous clayey and kaolinitic interbeds. Gebel El‐Gunnah has the largest sand stone reserves in Sinai. There are

more than 3 billion tons of high quality silica sands in more than 16 localities in Egypt.

Mining of unconsolidated sand deposits is done by using front‐end loaders, scrapers, or bulldozers. Material is dug,

excavated and the loaded into trucks to the processing plant. In some cases hydraulic dredges with a suction pump

excavate the sand and pump the material to the plant. In the case of well consolidated deposits, conventional drill‐

and blast methods are used, where the stone is mucked, hauled, and transported to the crushing section in the

processing plant.

In Egypt, surface mining technique is used for mining silica sand. The ore is drilled and blasted using Anfo and

gelatin for blasting. Bench height is around 10‐12 m. The broken rock transported to a size reduction and screening

section to be prepared for washing and processing.

The applied mineral processing units are arranged in simple flow‐sheets. They consist of screening, washing, and

classification. Sometimes the classified product is leached using diluted inorganic acids. Most of the working sites

use sea water followed by fresh water due to the scarcity of the fresh water in these areas. In some sites, magnetic

separation is used. Academic research work investigated the use of gravity separation and/or froth flotation. The

grade of the final sand product depends on the purity of the feed and the mineral processing steps taken for

cleaning the ore.

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25

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Mineral Industry in Egypt– Part II Non-Metallic Commodities – Silica Ores

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