IMBP017 - Ontario Wollastonite: Uses, Markets - Geology Ontario

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Industrial Mineral Background Paper #17

Ontario Wollastonite: Uses, Markets and Ontario's Potential as a Future Producer

By:

Dr. Janet Springer

Mineral Development Section

Ministry of Northern

Development and Mines

1994

DedicationDedicated to our friend and colleague, Dr. Janet Springer, whose productive career was tragically cut short on Janu ary 12, 1994. A tireless worker for Ontario's mining industry, Janet was also deeply committed to encouraging women in non-traditional roles. We all miss her enthusiasm and curiosity.

Industrial Mineral Background Paper 17

Queen's Printer for Ontario, 1994

ISSN 0228-7811 ; 17 ISBN 0-7778-2618-6

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Canadian Cataloguing in Publication Data

Springer, Janet.Ontario Wollastonite: uses, markets and Ontario's potential as a future producer

(Industrial mineral background paper, ISSN 0228-7811 ; 17)

ISBN 0-7778-2618-6

1. Wollastonite-Ontario I. Ontario. Mineral Development Section II. Ontario. Ministry of Northern Development and Mines. III. Series

TN948.W6S67 553.6 C94-964031-X

Every possible effort is made to ensure the accuracy of the information contained in this report, but the Ministry of Northern Development and Mines does not assume any liability for errors that may occur. Source references are included in the report and users may wish to verify critical information.

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Parts of this publication may be quoted if credit is given. It is recommended that reference be made in the following form:

Springer, Dr. Janet. Ontario 1994 Wollastonite: Uses, Markets and Ontario's Potential as a Future Producer; Ontario Ministry of Northern Development and Mines, Industrial Mineral Background Paper 17, 28 p.

Journal-1000-94

Gette publication scientifique n 'est disponsible qu'en anglais.

v Ontario y

Ontario Wollastonite

Contents 1. Foreword . . . . . . . . . . . . . . . . . . l

2. Executive Summary . . . . . . . . . . . . . 2

3. Introduction . . . . . . . . . . . . . . . . 4

What is Wollastonite? . . . . . . . . . . . 4

Why is WoUastonite Valued? . . . . . . . 4

4. Applications by Market Segment . . . . . . 7

Ceramic Applications . . . . . . . . . . . 7

Metallurgical Applications . . . . . . . 8

Asbestos Substitution . . . . . . . . . . . 8

Plastics Applications . . . . . . . . . . . 9

Paint and Coatings Applications . . . . . 9

Various Other Applications . . . . . . . 9

5. Geological Setting of Wollastonite . . . . 10

Geological Setting of Ontario Wollastoite 10

Setting l . . . . . . . . . . . . . . . 11

Setting! . . . . . . . . . . . . . . . 11

Settings . . . . . . . . . . . . . . . 11

Field Indicators for Wollastonite . . . . 11

6. World Production and Consumption ofWollasonite . . . . . . . . . . . . . . . 14

Two Material Qualities . . . . . . . . . 14

Comparison With Other DepositsWorldwide . . . . . . . . . . . . . 15

Evaluation of Quality Wollastonite . . . 18

Possibilities for a SuccessfulOntario Competitor . . . . . . . . . 18

7. Conclusions . . . . . . . . . . . . . . . 20

8. Selected References . . . . . . . . . . . . 21

Industrial Mineral Background Paper 17 Hi

1. Foreword Wollastonite is a mineral with a myriad of unique characteristics which lend themselves to ever increas ing applications in ceramics, fillers for plastics and paints, thermal and electrical insulators and fluxes and wetting agents for glazes and metal melts. Ontario is not yet a producer of wollastonite, but significant wol lastonite deposits are present in eastern Ontario. On tario's known deposits are located in the thermal aureoles of alkaline affinity intrusions or within high grade metamorphic terrane in the Grenvillian Central Metasedimentary Belt. The potential for discovering more wollastonite deposits in Ontario is excellent.

With this potential and recognizing eastern Ontario is well situated near land and water transportation corridors, the Commodities staff of the Mineral Devel opment section initiated this wollastonite study. The purposes of this particular Industrial Mineral Back ground Paper (IMBP) are to:

* identify the properties of wollastonite and relate these characteristics to its various applications

* describe the wollastonite markets and each prod uct's specifications

* summarize Ontario's geological settings for wol lastonite deposits and compare Ontario's deposits to present producers around the world.

Wollastonite's product diversity is increasing and this offers a favourable market opportunity for On tario's industrial mineral industry to explore and de velop wollastonite deposits.

It is hoped that increased knowledge of the wollastonite market and Ontario's geological potential provided by this IMBP will stimulate activity which will lead On tario into the ranks of wollastonite producers and proc essors in a very short time.

Mineral Development Section: Commodities Mining and Land Management Branch Ministry of Northern Development and Mines


2. Executive Summary

Wollastonite is a natural calcium silicate (CaSiOa) which is valued for a wide variety of unique properties. It is a white mineral which crushes to acicular frag ments with aspect ratios of up to 20:1. This charac teristic lends mechanical reinforcement in its application as a filler for ceramics, plastics and paint. Wollastonite is generally very white and it melts sharply at 15400C. This sharp melting point makes it useful as a welding flux or as an additive to ceramic glazes. Its anhydrous nature also makes it easier and faster to fire ceramics which have a wollastonite con tent. Similarly, wollastonite's low straight-line expan sion coefficient improves glazing and firing of ceramics and reduces shrinkage and thermal shock. This unique mineral also possesses a low dielectric constant and low heat conductivity. The former makes it a good electrical insulator in plastics and powerline insulators. Low heat conductivity allows wollastonite to be used in kiln liners and special insulating paints. When wollastonite is employed in paints it is alkaline, which counteracts the effects of acid rain and resists rusting in paint cans. Wollastonite is also finding wide spread application as a substitute for asbestos. Wollas tonite is a truly unique mineral.

In general, the market for wollastonite can be di vided into low aspect (less than 5:1) material screened from 10 to 75 microns and a high aspect market, which demands aspect ratios of 10:1 or more. World produc tion of wollastonite in 1990 was 366 000 tonnes, prin cipally supplied by the United States (389fc), China (279fc), India (109fc) and Finland (99fc). Asia (3896), Europe (319&) and North America (249fc) were the largest consumers of wollastonite.

Wollastonite forms by the thermal reaction of lime stone rocks with silica. In Ontario, wollastonite occurs in three geological settings; as a primary mineral in a carbonatite intrusion, in the thermal aureoles of late Proterozoic intrusions in the Grenville Structural Prov ince and in high grade Grenvillian metamorphic ter rane. The latter two settings appear to offer the most promise for commercial deposits, particularly in the Central Metasedimentary Belt of eastern Ontario. In Httsburg township, 30 km northeast of Kingston, granulite grade regional metamorphism has altered limestone beds to a wollastonite - diopside assemblage, containing 50 to 609& wollastonite content in 30 m thick beds. The Deloro granite in eastern Ontario has exten sive areas of wollastonite developed in its thermal


aureole. Wollastonite content in the largest body aver ages 30^. The grades, properties of the wollastonite and reserves of Ontario's known wollastonite deposits compare very favourably with the principal producing deposits in other countries.

In addition, Ontario contains extensive, unex plored carbonate rocks in the Central Metasedimentary Belt. These rocks have been cut by alkaline affinity intrusions or overprinted by areas of granulite grade metamorphism. These geological settings offer ideal exploration opportunities for wollastonite deposits in areas situated close to transportaion and infrastructure.


3. Introduction Industrial minerals have special natural properties that make them useful in many everyday applications. Wollastonite is one such Ontario mineral. It appears in many common daily uses, but it is not widely known. The mineral's special properties were not used com mercially until about 1950, but since then its impor tance has steadily increased. Deposits of good quality wollastonite are uncommon and so the mineral com mands a good price in the right markets. This paper outlines the properties that make the mineral valuable; summarizes the geological setting and field indicators of recently mapped Ontario deposits; briefly examines world production and consumption of the mineral; places Ontario wollastonite in the context of other known deposits; outlines highlights of evaluation and gives a profile of a successful competitor in the market.

What is Wollastonite?Wollastonite is a natural calcium silicate with the

chemical formula CaSiOs and a theoretical composi tion of 48.3^o CaO, Sl.7% SiO2. It is typically found in altered high-calcium limestones, which have been strongly heated and recrystallized either by deep burial or by contact with granitic intrusions.

Why is Wollastonite Valued?

Wollastonite has a range of special properties that make it better suited than other minerals for use in ceramics and many other special applications. Its chemistry, long-grain particle shape and thermal char acteristics make it suitable for wide use in dishware, sanitary ware and interior tiles. It grinds to a powder of fine strips which give strength and flexibility to plas tics, unfired ceramics and special paints. It withstands friction and high temperature which makes it useful in brake linings and insulator panels.

Some of wollastonite's special properties are listed in Table l, together with related industrial applications.

Wollastonite is the only commercially available pure white mineral that crushes to a wholly acicular (lath-like) product (see cover photograph). Its cleavage fragments are elongate, matchstick-like rods with a length-to-width ratio (aspect ratio) of up to 20:1 and commonly 7 or 8: l. This cleavage behaviour results in


a filler mineral with unique reinforcing properties in mixtures such as thermoplastics and ceramic body- ware.

The mineral usually occurs as aggregates of white, bladed or needle-shaped crystals with a glassy or pearly lustre. It has a hardness of 4.5 on Moh's scale and a specific gravity of 2.87 to 3.09. It melts sharply at 15400C and has a very low coefficient of expansion. It

shows brilliant reflectance and exhibits low conductiv ity of both heat and electricity.

Chemically, wollastonite is largely inert. Its low dielectric constant makes it a good electrical insulator. In addition, it is a good thermal insulator.

Wollastonite is anhydrous, and the absence of crys talline water is an important advantage in contrast to hydrous minerals commonly used in ceramics. It does

Table 1. Properties, benefits and uses of wollastonite

Property

Chemical Composition

CaO content

No crystalline H2O

No CO2 radical

Low Fe, Ti, Mn content

Strongly alkaline in solution

Inert

Low alkali content

Physical properties

Low temperature fusion without melting (sinters)

Melts sharply without bubbling at 15400C

High surface energy of molten mineral

Low dielectric constant

Low heat conductivity

Hardness s 4.5

Retains abrasivity at high temperature

Acicular cleavage particle

Low straight-line expansion coefficient

Low oil or colour absorption

High whiteness

High reflectance (92 - 96 0Xo of MgO, standard white)

Benefit/Use

Improves glaze strength and finish of alkaline glazes. Matt finish in low-fired glaze mixtures.

No steam or bubbles with heating. Faster drying of ceramic body mixtures. Improvement on older formulations.

No COa evolved on heating. No bubbles or pinholes in glazes.

Whiteness remains on firing ceramic or glaze. Melting temperature stable.

pH 9.9 maintains alkalinity in acetate paints; counteracts acid rain damage, rusting in paint cans.

Stable, predictable ceramic body and filler material.

Improves electrical insulation properties.

Suitable for fast-firing of ceramic body and glaze. Fuses readily with other constituents (Al, Si).

Useful as welding flux, glaze additive.

"Wets" metal and silicate melts well. Prevents oxidation in welding or casting of metals.

Good electrical insulator in plastics, power line insulators, special paints.

High heat resistance used as thermal insulator in kiln liners, special paints.

Abrasion resistant, non-skid plastics, paints.

Good for abrading tools, aircraft brakes.

Mechanical reinforcement in ceramic body, plastics, panel board, exterior paint. Improves acoustic properties and weather resistance in dried paint. Conducts HaO from ceramic body; speeds drying and reduces bloating. Speeds flattening of paint films.

Improves both ceramic glaze thermal and body. Reduces crazing shrinkage, and thermal shock.

Reduces binder and pigment needed in paints, plastics.

Good base for ceramics, paints, plastics.

Ceramics and paints stay bright and colour-true.


not absorb oils or water. Its high surface energy means that it is easily wetted by silicate melts or solutions.

The mineral is brilliant white when pure, but may be tinted grey or brown by iron, manganese, magne

sium or strontium replacing calcium in the crystal structure. Low impurity values are important to good quality wollastonite and may determine whether the mineral is economically exploitable.


4. Applications by Market Segment

Ceramic ApplicationsFigure l and Table 2 show the market share of

different grades of wollastonite. Most wollastonite is shipped for ceramic applications, mainly for products that are mass produced in fast-firing tunnel kilns. Com mon examples are wall tiles and glazed sanitary ware.

The addition of wollastonite to body mixtures and glazes has revolutionized ceramic production. Tradi tional clay bodies contain minerals (talc, dolomite, calcium carbonate) that release water vapour or carbon dioxide gas on heating. The gases cause the clay body to puff up, and fast firing does not allow the condition to stabilize. Difficulties arise with rapid changes of temperature which can cause glazes to shatter and objects to distort.

The addition of wollastonite counteracts many of these difficulties. Glass mixtures and glazes melt evenly at lower temperatures and, because thermal expansion is low and little gas is evolved, temperatures can be raised and lowered rapidly without causing distortion or cracking. Ware made with wollastonite can be fast fired and needs only a single firing. A 50*9k addition of wollastonite in some processes has reduced the firing cycle to one hour from 20 to 70 hours. Time saving stems from a shortened drying stage, rapid fluxing of the body materials and uniform flash sinter ing of the body. These properties allow an increase in mechanization which means that products are fired rapidly to increase output. The increased strength of the unfired ("green") ware has also allowed highly auto-

Ceramtes 54V.

Metallurgy19V.

(HM1MI1991)

Asbestos Substitution 15V.

Figure 1. Principal uses of wollastonite 1990 esti mates.


mated handling, thinner and stronger ware, less break age and smaller, more energy efficient kilns.

Wollastonite's many benefits in the ceramics in dustry all relate to its mineralogical and chemical prop erties.

1. The alignment of the match-like cleavage laths gives a mechanically strong unfired clay body that stands up better to high speed pressing techniques.

2. The laths conduct moisture out of unfired tiles, thereby reducing the incidence of steam swelling.

3. The fired ware is free of distortion and shows high impact strength so that there is less breakage.

4. Wall tile surfaces develop good acoustical proper ties.

5. The mineral has a low coefficient of expansion, which shows a straight-line increase with tempera ture. This counteracts the shrinkage commonly produced by companion minerals. Body cracking and glaze defects are reduced.

6. Wollastonite can readily be processed to reduce calcite impurities, so that CO2 given off is less than 19& LOI. This low value is very favourable in comparison to the gas volume generated by tradi tional body minerals.

7. The low gas content means little bubbling of the melt and few pin-holes in glaze surfaces.

8. The mineral can be selected for minimal impurities of iron, titanium and manganese. Whiteness and colour purity remain on firing, giving true, bright colours.

9. Because alkali elements or impurities are absent, the mineral is an excellent insulator.

10. it has a low sintering temperature (991 to 11960C) and because it fuses readily with alumina and silica the clay body flash-sinters uniformly throughout.

11. It neutralizes glaze formulations, thus increasing strength and surface finish. This allows a choice of surface finishes at low temperatures.

Metallurgical Applications

The low temperature flux property of wollastonite makes it an important additive for use in the continuous casting process for steel-making. As the stream of molten steel pours from the refining ladle into the refractory tundish, a powdered flux containing wollas tonite is applied. This melts to provide a "wet" coating to the casting channel which gives the steel a smooth finish and minimizes surface defects. In welding for mulations, wollastonite reduces sparking by efficiently wetting metal surfaces. Its good rheological properties at high temperatures protect surfaces from oxidation during welding, which is especially useful in difficult, continuous welding of complex, high-nickel, heat re sistant alloys.

Asbestos SubstitutionWidespread restrictions, because of the associated

health risks, have been placed on asbestos, both in the United States and Europe. The largest use of asbestos is for mechanical strengthening of cast concrete piping. The long cleavage fragments of wollastonite with a

Table 2: Principal Uses of Wollastonite by Typeacicular

Asbestos substitution *Performance filler *FillerPaint +CeramicsMetallurgical flux* ~ Primary use+ a Secondary useModified from Industrial Minerals Magazine, January 1986

micronized acicular powder


high aspect ratio can practically mimic asbestos in this application. In heat-resistant panel board or high tem perature liners for aluminum smelting, wollastonite's low thermal behaviour under friction at high tempera tures means that wollastonite can be used to replace asbestos in severe-service applications such as aircraft brakes.

Plastics ApplicationsWollastonite competes well with other white fillers

in the plastics filler market because it also contributes special properties to the finished material. It possesses the whiteness and high brightness that top quality fillers must attain, but in addition it improves tensile, impact and flexural properties. As in ceramics, it reduces shrinkage on setting. It also increases wear resistance and friction in non-slip flooring. The mineral has little absorbed water in comparison with talc or carbonate fillers and does not influence the resin mixtures. It also does not absorb the plasticiser fluids. At high mineral loadings it maintains a low viscosity. The low water absorption means the plastics surface is water and stain-resistant. The low electrical conductivity allows manufacture of insulating plastics. For example, a 4096 wollastonite loading in polypropylene gives a material with very favourable electrical insulating properties.

Paint and Coatings Applications

As a paint filler, the white colour and brightness of wollastonite makes it usable in the palest tints, giving

clear bright colours. The low absorption reduces oil binder requirements in oil paints. Wollastonite is strongly alkaline in suspension (pH 10), making it suitable as a constituent of a good metal priming paint. In polyvinyl acetate paints that decompose with time to acetic acid, wollastonite buffers and stabilizes the paint, especially in acid environments. The grain shape en courages rapid levelling of paint films and promotes even film thicknesses. Exterior house paints with wol lastonite are "self-cleaning" because the filler dusts off revealing a fresh surface. The intermeshed grain struc ture improves scrubability and weather resistance. Spe cial paints use the abrasive or non-conductive properties of wollastonite to give floors that are non- slip or insulating. In the paint can, wollastonite's spe cial attributes keep the pigment well dispersed, gives a soft bottom sediment that is easily stirred, and prevents cans from rusting inside.

Various Other ApplicationsSeveral authors (Andrews 1970, Sargent 1972)

discuss a wide range of special uses for wollastonite, such as insulators that discharge very little of the power carried by the lines, ceramic fillers, friction materials used at high temperatures for such applications as aircraft brakes and abrading tools for cutting high strength alloys.


5. Geological Setting of Wollastonite

Wollastonite forms by thermal reaction of lime- rich rocks with silica. This may occur where interlayered marbles and quartzites are regionally or contact metamorphosed, where silica is metasomatically added to calcareous host rocks in the thermal aureoles of plutonic bodies, or where acidic intrusions are contami nated with lime-rich country rock.

Eastern North America has become the centre of world wollastonite production, with the Grenville Structural Province forming the geological focus of attention. Part of this Province, the Central Metasedi- mentary Belt (CMB), contains pure, low-magnesia marbles interbanded with quartzites, which have been affected by regional metamorphism and by the thermal- chemical overprint of several suites of intrusions.

Important wollastonite deposits in New York State are found where regionally metamorphosed Grenvil- lian marbles have been overprinted by the contact effects of anorthosite intrusions. In the Quebec portion of the Central Metasedimentary Belt, work by Fournier and St. Seymour (1992) has confirmed two local envi ronments for wollastonite: low grade disseminated de posits which formed marginal to pre-tectonic anorthosite intrustions (1.3 Ga) where later regional metamorphism provided conditions suitable for syn tectonic growth of the mineral and patchy epigenetic veins that cross-cut regional gneissosity, in which wol lastonite concentrations are higher and a larger propor tion is long-grain material, but total volumes are lower.

Geological Setting of Ontario Wollastonite

Wollastonite occurs in three geological settings in Ontario:

1. as a primary mineral in a single carbonatite intru sion

2. in the thermal aureoles of a number of late Protero zoic intrusions that cut rocks of the Grenville Struc tural Province

3. in certain high-grade Grenvillian metamorphic terranes.

10 Ontario Wollastonite

Setting 1

To date, the wollastonite of the Prairie Lake car bonatite intrusion seems to be the only occurrence of this type. This body, which cuts Archean rocks of the Wawa Structural Province, is one of a suite of Late Precambrian alkalic intrusions dated at about 1033Ma. However, wollastonite is not found in other bodies of comparable age. In 1730m of diamond drilling, several intersections, averaging 30 to 759fc wollastonite, were reported (Sage 1987). Samples of pegmatitic wollastonite-nepheline showed coarsely crystalline wollas tonite ranging from 5 to 150 mm in length. The mineral chemistry is shown in Table 3.

Setting 2

Quality wollastonite is found locally in marble zones of the Central Metasedimentary Belt (CMB) of the Grenville Structural Province where younger plu- tons, from an intrusive episode at about 1245 Ma, cut lime-rich host rocks (Fyon and Easton 1992). Contact aureoles showing thermal and metasomatic alteration surround intrusions of this age. They are found in terranes of lower metamorphic grade. In the Elzevir terrane (Figure 2) eight wollastonite deposits (Figure 3) encircle the west margin of the Deloro granite (MacKinnon 1990). Another deposit in this terrane, the Crowe Lake wollastonite prospect, abuts the eastern margin of the Cordova gabbro.

In the Sharbot terrane, carbonate roof pendants in the Mountain Grove gabbro host the Hawley wollas tonite prospect. Prior to 1992, Ram Petroleums Ltd. drilled 19 holes at the Hawley prospect which indicated 2.5 million tonnes of ore grading 329fc wollastonite (LeBaron et al 1992). The wollastonite-calcite-minor diopside ore occurs in a 35 by 200 m zone. The location of all these is shown on Figure 2 and they are fully described by MacKinnon (1990).

Setting 3

Wollastonite of regional metamorphic origin is found in specific high-grade terranes of the Grenville Structural Province. (Fyon and Easton 1992) where marble horizons in the CMB have been affected. Figure 2 shows a number of occurrences concentrated in the Frontenac granulite terrane and others in the Mazinaw,

Bancroft and Elzevir terranes. These areas of unex plored high-grade rocks offer great opportunities for prospecting.

This type of setting is currently being explored by industry (LeBaron et al. 1992) in Pittsburg Township, in the Frontenac terrane of the Grenville Province.

The Pacific Coast Mines Inc. wollastonite prospect is located about 30 km northeast of Kingston along the east side of Highway 15 just south of Seeley's Bay, in lots 36 to 38, concession X, Pittsburgh Township, Frontenac County and lots l to 3, concessions VI and Vn, Rear of Leeds and Lansdowne Township (Leeds Geographic Township), Leeds County, (LeBaron et al. 1992).

Here, thick units of limestone and pure sandstone have been regionally metamorphosed to granulite grade. Later contact metamorphism by a mafic intru sion has amplified the metamorphic changes. A simple wollastonite-diopside mineralogy has been developed, with minor quartz and sulphides present. The principal layer is 30 m thick and contains 809& wollastonite as 2 to 5 mm equant grains. Reserves from the current mapped area (800 by 500 m) indicate a very substan tial orebody grading 50 to 609& wollastonite. The min eral crushes to long, splintery fragments whose length to width ratio (aspect-ratio) shows favourable values of up to 20:1.

Field Indicators for Wollastonite

Prospective targets for wollastonite are margins of fluid-rich intrusive bodies that cut pure limestone host rocks, or high-grade regionally metamorphosed terranes of interlayered pure quartzite and marble.

Quality wollastonite is commonly found in very white, coarse-grained marbles. The low iron content required to produce prime quality wollastonite means that even if some impurities are present, the rocks will appear pale grey or green. TTie presence of coarse calcite plus quartz, either as bands or veins, indicates prospective areas in the field.

Where the starting materials are simple and pure (clean limestone and well sorted quartzite) the ideal

Industrial Mineral Background Paper 17 11

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mineral assemblage formed is calcite, quartz and wol lastonite. However, in practice, impurities of iron and magnesia mean that diopside, tremolite, idocrase and garnets may be present.

Under the hand lens, pure wollastonite is white with a glassy to transparent-translucent lustre. It is softer (4.5 to 5 on Moh's scale) than quartz (7) and harder than calcite (3). Wollastonite, even in massive form, shows tabular, bladed or acicular habit. The crystals are elongated parallel to the b-axis, and show a pair of cleavages at 84.50 . In contrast, calcite is

Regional Metamorphic

o Contact Metamorphic

Figure 2. Map showing the location of the Elzevir terrane.

elongated parallel to the c-axis and shows a distinct 600 rhombohedral cleavage. Some wollastonites fluoresce in either or both short or long-wave ultraviolet light, showing colours in the yellow-orange, pink-orange or rarely blue-green range.

In contrast, pale iron-free tremolite which also shows a coarsely bladed habit and has a hardness similar to wollastonite (5 to 6) can be distinguished by a pair of perfect cleavages at 560. Tremolite is insoluble in concentrated hydrochloric acid, but wollastonite de composes.

Figure 3. Wollastonite deposits in the contact aure ole of the Deloro pluton, Marmora Township.


6. World Production and Consumption of Wollastonite

The principal world producers and their market share are summarized in Figure 4. It is apparent that the United States dominated production in 1990, but that China has a substantial position as a supplier. The principal users of wollastonite by geographical share are shown in Figure 5. Asia is the largest consumer, as a consequence of the important Japanese ceramics industry, followed by Europe and North America. An estimate of world production for the years 1975 to 1990 is graphed in Figure 6.

Two Material QualitiesIn practice, two different wollastonite markets ex

ist; one which uses low aspect ratio material (up to 5:1) commonly screened to sizes from 75 to 10 microns, and one which demands aspect ratios of 10:1 and more. "Micronized" wollastonite is a specialty product within the high-aspect ratio market in which the acicular min eral is sized and screened to exacting pre-set size ranges. The applications for these different types are summarized in Table 2. This table, together with Table 4, shows that coarse acicular wollastonites command the best prices. Those deposits that do not have the inherent advantage of large grain size can add sales value by careful processing which is directly geared to customer needs.

United States38V.

Others IV. Namibia T/t Germany 3V.

Mexico 5V.

Turkey 5V.

(Hanwl1991)

Figure 4. World production of wollastonite in 1990 (preliminary figures) 366,000 tonnes.


Comparison With Other Deposits World Wide

The principal wollastonite deposits of the world are shown in Table 5. The size and grade of the Ontario deposits can be judged in this context. Mineralogical and chemical data from some of these offshore deposits are compared against Ontario data in Tables 3 and 6. Initial examination of Ontario wollastonites (Sage 1987, Mackinnon 1990) suggests that iron values are as low as many commercial concentrates.

The Deloro deposits in Marmora Township are Ontario's best described wollastonite bodies (Mackin non et al. 1989). They lie about 3 km from the town of Deloro in Hastings County, about 175 km northeast of Toronto. Surface stripping and diamond drilling over the past four years have outlined about 3.2 million tonnes grading 27 to 3796 wollastonite and 50 to 6596 calcite (Barker 1992). Wollastonite with calcite and minor pyrite occurs in four zones of silicified dolomite skarn, as nodular aggregates l to 20 cm across, or as horizons of acicular crystals in a calcite matrix.

Processing of these ores has yielded clean concen trates of wollastonite with moderately good aspects ratios, and calcite (Andrews 1988,1993; Barker 1992). Recent beneficiation trials (Barker 1992) showed 20 to

Latin America 6V.

North America 24V.

(Hum* 1991)

Figure 5. Estimated world consumption of wollas tonite for 1990.

3096 contained wollastonite of which flotation recov ered 70 to 9596.

In the -300 micrometer range, beneficiation pro duced concentrates with aspect ratios of 2:1 to 4:1. Fractions in the 150 micrometer range gave 4:1 to 8:1 aspect ratios. In the -325 mesh fraction 7096 showed aspect ratios of greater than 3:1. Cationic flotation yielded fractions of 86 to 9396 wollastonite with 0.57 to 0.6296 FC2O3. A combination of magnetic separation and anionic calcite flotation gave 86 to 8996 wollas tonite with 0.33 to 0.8296 FeiOs. Whiteness averaged 96.596. The calcite concentrate analysed 93.7 to 97.596 CaCOs (Andrews 1993).

The Hawley wollastonite deposit in Olden Town ship about 6 km south of Mountain Grove has reported reserves of about 2.5 million tonnes grading 32 to 3596 wollastonite (MacKinnon 1990). Preliminary work showed aspect ratios of 10:1 to 12:1. Ram Petroleums Ltd. continues to drill and bulk sample the deposit. A process flowsheet, probably using froth flotation, is being developed to separate the calcite fraction, which is being tested as a filler in several markets (Industrial Minerals 1993).

Seeley's Bay wollastonite prospect, located in Pittsburgh Township, is held by Pacific Coast Mines Inc., a subsidiary of the United States Borax and Chemical Corporation. Detailed geological mapping

Uhtod States

1975 1977 1979 1981 1983 1985 1987 1989

YEAR

(from Ham*l 1991)

Figure 6. Estimated world production of wollastonite from 1975-1990.


Table 4. Wollastonite Prices (SUS/tonne, October, 1990)Dimension Vanderbilt

(f.o.b. mine)200 mesh/75 microns 1 1 0-1 30325 mesh/45 microns 1 20-1 90400 mesh/38 microns475 mesh/30 microns1250 mesh/10 micronsSource: Industrial Minerals Magazine, October 1 990

NYCO granular(f.o.b. mine)140-195260

NYCO acicular(f.o.b. mine)285-290190-205310420570

Oy Partek(c.a.f. U.K.)

360-490210-215

Table 5. Major Wollastonite Deposits WorldwideCountry State/Province Deposit

South Africa Namaqualand Caries

Canada Ontario Deloro

Pittsburgh tp.Hawley ZincPrairie Lake

Quebec Morin HeightsSt-Onge

China JilinAnhuiYunnanJiangxi

United States New York LewisOak HillHarrison

Nevada Gilbert

Finland LappeenrantaSavitaipale

Greece Trace Kimmeria

India Rajastan Khera TarlaBelkapahar

Kenya Kajiado Lolkidongai

Mexico Chiapas Santa FeZacatecas La BlancaSonora San Martin

Namibia Usaskos

New Zealand Nelson Takaka Hill

Sudan Dirbat

Turkey Baliskesir KepsutBursa Tahtakopru

USSR Ouzbkistan Koytash

Yugoslavia Siberia Mouth Kapaonik(1) MV: In ground value; Pro: In(2) Proven and probable reserves

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and a total of 49 diamond drillholes, drilled in 1992, defined an 800 by 500 m area of wollastonite-diopside which averages 50 to 609& wollastonite (LeBaron et al. 1992).

The ore produces ground separates with high as pect ratio cleavage fragments. In the -200 +70 mesh size range, aspect ratios of up to 20:1 are achieved. Magnetic separation removed up to 2096 waste diop side and pyrrhotite. Further testing will show if simple air separation will suffice or whether flotation will be needed to achieve acceptable purity levels (LeBaron, personal communication, 1992).

Evaluation of Quality Wollastonite

Ideally a commercial product should approach the chemically ideal formula of wollastonite and possess specific mineralogical properties. A quality metamor phic wollastonite deposit should have the following characteristics:

* inherent purity of the lime carbonate host rocks, with little iron or magnesia that may produce dark mineral phases

* thick host rock units to produce massive mineral concentrations

* large crystal size so that crushed material will remain coarsely fragmental

* strongly elongated crystal habit to enhance the aspect ratio of the cleavage product

* little intergrowth with quartz, calcite or tremolite to reduce grinding and separation problems

* iron values below G.5% in solid solution in CaSiOs

* combined Fe, Mg Al and Mn below 39fc

* loss on ignition less than 5 tfa and preferably below 19& for ceramics uses. This is an indirect measure of the carbonate present

* few to no inclusions, particularly of the iron-rich phase

A complete evaluation, which can begin with hand lens examination of samples and intergrowths, will need polished slabs and thin sections for textural analy sis of the mineralogy. Microprobe examination of crys talline wollastonite is needed to test the purity level.

Trial processing regimes will depend on the par ticular features of each deposit. As quality is very sensitive to contamination, extraction of bulk samples and the transportation to test facilities must be carefully performed. Wollastonite is abrasive and moderately tough so pebble milling should use ceramic spheres. Attrition milling or special jet mills can improve the aspect ratio. Pure concentrates can be achieved using combinations of wet and dry magnetic separation or flotation with various reagents.

Quality characteristics will be defined by particle size, distribution and shape; brightness measured against a standard MgO powder and oil absorption. Purity is assessed by iron content and loss on ignition.

Possibilities for a Successful Ontario Competitor

Forecasts of market demand for powder and fibre wollastonite have been estimated to the year 2000

Others Plastics

Metallurgy

Substitutes

Ceramics

1990 1992 1994 1996 1998

YEAR

(modrflMl from Name) 1991)

2000

Figure 7. Demand forecast by industry sector for wol lastonite type 1990-2000.


Table 7. Natural Wollastonite Demand TrendsIndustry 1986 Volume

(tpy)Plastics Ceramics Paint Metallurgy Others

Total Exports

22,800 14,300 6,700 6,200 9,500

59,500 18,000

1986 Value (USSmllllons)

7.9 1.7 1.3 0.51

12.4 4.5

1989 Volume(tPV)29,500 16,000 7,500 7,000

11,000

71,000 20,000

1989 Value (USS millions)

10.6 2 1.7 0.6 1.3

16.2 6.5

Annual Growth Rate Volume Value (0Xo)0.09 0.038 0.038 0.041 0.05

0.061 0.036

10.3 5.6 9.3 6.3 9.1

9.3 1.3

Grand Total 77,500 16.9 FromBrodmann 1991

91,000 22.7 0.055 10.3

(Hamel 1991). Figure 7 shows expected increases in the ceramics area for powder material and in both asbestos substitution and plastics reinforcement for fibre material. More detail of the expected performance of the North American market is shown by Table 7 (Brodmann 1991). Volume growth rates of over 49fc are predicted for all market segments, with the greatest increases forecast for plastics reinforcement in the automotive industry.

These predictions must be tempered by the present North American recession which had not developed its full force when the figures were obtained. However, this event and the strength of the Japanese car market are modified by other world events. Increasing living standards in the Third World, and recently, the oppor tunities offered by Eastern Bloc markets will undoubt edly fuel demand for ceramic grades, which is already the largest market Misgivings about the safety of as bestos will probably continue to encourage replace ment in the uses where wollastonite can compete functionally and where new technology has already been introduced.

The outlook for increasing world markets seems positive for a mineral of such diversity. For Ontario, success will depend on finding large bodies of high purity material, particularly if such material has large crystals and consequently long cleavage fragments.

A successful Ontario deposit should:

* be close to existing transportation routes, prefer ably to the Great Lakes' ports, as the material may well need to be custom-processed in Europe where technology and market intelligence are better de veloped

* contain l to 2 million tonnes of reserves

* grade more than 30*^ wollastonite

* have a crystal size that allows clean -H 200 mesh fractions to be produced

* show less than 19fc iron, and less than 396 combined impurities

* show very low to trace alkali coi.tents.


7. Conclusions There appears to be favourable market opportuni ties for a mineral whose properties have lent them selves to wider and more diverse applications with every research initiative that has been undertaken. In Ontario, the most promising prospective terranes are found in Grenville Structural Province, although intru sions of alkaline affinity should be checked elsewhere in the province. In metamorphosed marble rocks of the Central Metasedimentary Belt, both contact effects at the margins of intrusive bodies and high-grade regional metamorphism, provide likely geological settings, par ticularly where multiple metamorphic effects are over printed. Structural terranes of higher-grade rocks (Mazinaw, Bancroft, Elzevir, Frontenac), are target areas, and the granulite-grade Frontenac terrane seems particularly favourable.

At reconnaissance level, mixed quartzite-marble rock packages are likely sites for wollastonite to form. Pale coloured mineral assemblages and very low colour indices will indicate better chemical purity. Large grain size and elongate crystal form are probably indicators of a deposit that can be successfully beneficiated.

Crushed material that shows aspect ratios of greater than 15:1 in the * 200 mesh fraction point to premium quality.

A viable deposit must contain at least l million tonnes of reserves and be close to existing power and transportation routes, preferably adjacent to the St. Lawrence seaway.


8. Selected References

Useful references available from the Mines Li brary or from the Mining and Land Management Branch, 933 Ramsey Lake Road, Sudbury, Ontario, P3E 6B5.

Andrews, P.R.A., 1988. Beneficiation of two samples of wollas tonite from Marmora, Ontario; Division Report MSL 88-89 (IR), CANMET, Energy, Mines and Resources Canada

, 1993. Summary Report No. 18: Wollastonite; Division Report MSL 93-10(R), CANMET, Energy, Mines and Re sources Canada

Andrews, R W, 1970. Wollastonite; Institute of Geological Sci ences, Her Majesty's Stationary Office, London, 114p.

Barker, A. L., 1992. Technical and commercial aspects of the Deloro Wollastonite Deposit in Marmora, Ontario; in Pro ceedings Industrial Minerals '92. Blendon Information Serv ices, Willowdale, Ontario

Brodmann and Co., Alsobrook and Co., and ORTECH Interna tional, 1991. Synthetic minerals: potential materials from Ontario resources; Industrial Mineral Background Paper 15, Ministry of Northern Development and Mines, 45p.

Fischl, P., 1991. Wollastonite and tremolite occurrences in British Columbia; Open File 1991-17 British Columbia Geological Survey, 48p.

Fournier, A. and St. Seymour, K. 1992. Geology and physical characteristics of wollastonite in Grenville Supergroup mar bles, Quebec; CIM Bulletin, v.85, no.957, p.62-67.

Fyon J. A. and Easton, R. M., 1991. Metallogeny of the Grenville Province; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, Part 2, p.1217-1252

Hamel, Denis, 1991. Profil International du Marche de la Wollas tonite; Publication ER 91 -5057, Ministere de L'Energie et des Resources du Quebec, 37p.

Industrial Minerals, 1993. World of minerals -Canada; July, 1993, p. 9-10

Keeling P.S., 1963. The wollastonite deposit at Lappeenranta (Willmanstrand) S.E. Finland; Transactions of the British Ceramic Society. Volume 62, Number 10.886p.

LeBaron, P.S., Kingston, P.W., Papertzian, V.C., van Haaften, S., Meyn, H.D., and Caley, W.F, 1992. Southeastern Resident Geologist's District; in Report of Activities 1992, Resident Geologists, Ontario Geological Miscellaneous Paper 161, p.371-387.

MacKinnon, A, 1990. Wollastonite in Southeastern Ontario; Open File Report 5715, Ontario Geological Survey, 289p.


MacKinnon, A, Kingston, P.W., and Caley, W.F., 1989. Wollastonite in Eastern Ontario; CIM Bulletin, February 1989, p.61-67

Power, T., 1986. Wollastonite: performance filler potential; Industrial Mineral Magazine, Jan. 1986, p. 19-34

Sage, R.P., 1987. Geology of carbonatite - alkalic rock complexes in Ontario: Prairie Lake carbonatite complex, District of Thunder Bay; Ontario Geological Survey, Study 46,91p.

Sargent, D.E., 1972. The uses of wollastonite; Eastern Adirondack Development Commission, 11 Ip.


IMBP017 - Ontario Wollastonite: Uses, Markets - Geology Ontario

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