Introduction

Among these, the dimension and ornamental stones ASM is growing and spreading throughout the country, at the same rate of the formal, medium-sized and big companies growing, as a consequence of the Brazilian sector growth in the international market of dimension stones.

That increasing number of people and places in the ornamental and natural stones business, most of them lacking capacitation, technology and financial resources, generates environmental health impacts that those producers individually, cannot afford to heal. And, of course, a very complex legal framework makes their legal licensing almost impossible to be accomplished.

Recognizing the contribution of ASM to Brazilian economy and because its social importance, mainly due to the positive effect on incomes distribution among poor communities in hundreds of places all over Brazil, policy makers are looking at this sector with different eyes. If the legal mines occupy around 135 thousand workers, the number of informal artisanal miners could reach another 130 thousand people.

As an example of this more comprehensive look, a new industrial policy was set in March 2004 containing, among other resolutions, definitions and tools to render possible strong support to Small Mining Enterprises (SMEs), especially those located on production clusters. The definition for an industrial or production cluster was slightly changed, compared to the traditional economic thinking, to suit better the Brazilian SMEs situation.

For the mineral sector, the possibility to promote ASM was quite positive since new support funds were created and with the help of government and/or NGOs many mining communities may change their ways of organization and production to reach better technical, market and environmental standards. Another important change was the name of such mineral sites. Before, almost all of them were named 'garimpos' and understood as “out of law” and conflictive sites. Now they can be recognized by a new definition: “mineral-based local clusters”.

Technological support to mineral clusters

As a result, CETEM (Centre for Mineral Technology) was asked to lead three mineral APLs and to hold some kind of technical support on other two, which respectively are: the APLS of Natural Stone of Santo Antonio de Padua (State of Rio de Janeiro), the Limestone of Cariri (State of Ceará) and the Opal cluster at the State of Piaui, all three located on poor or very poor regions. The other two are the Soap-stone cluster at Minas Gerais and the Ornamental Marble Cluster of Ourolândia, State of Bahia. After 8 years, since CETEM started its first APLs project, the evaluation of obtained results can be considered quite good.

As this article pretends to give an overview of solutions for the environmental problems for small scale dimension stone producers, only the two first of these APLs will be used as case-studies.

At the Padua natural stone APL, were around 6,000 people produces gneisses for cladding and pavements, together with other well skilled institutions’ professionals, the environmental and mining licenses are being obtained by a step-by-step process of technical improvements with small loans aid to stone producers.

Since the worst environmental problem created by these producers (as it happens in all of the ornamental stones ASMs) was the enormous amount of wastes (around 70% of the material extracted in the quarries), different solutions for each type of waste (quarry wastes and gross and fine wastes from the cutting process – see Figure 2) had to be found.

Rock wastes from the quarry and riprap from the tiling process are now been used for building applications other than tiles, such as paving, external walls and also as pebbles for gardening (made in an improvised ball mill), and also aggregates (by crushing and classificating the stone in small plants). Those small entrepreneurs developed all this by-products.

Maybe the most important technical result, this one developed by the professionals supporting the APL, was the wide spread use of a simple solid-liquid separation process that makes possible the recycling of 95% of the process water for stone cutting saws (Figure 3). The water recycling allowed the producers not only to drastically reduce their water consumption, but also to meet the environmental standards for their effluents discharges what was a problem before, because of the high content of suspended solids.

On the other hand, by using effluent treatment units, a new challenge appeared: what to do with the big amounts of very fine residues separated from the water?

The technical institutions involved made several studies for industrial applications of those fines (85% smaller than 44m) constituted of biotite, quartz and feldspars. They found different feasible uses for those fines, substituting other materials as clays or lime in ceramic, asphalt pavements and mortar composition. Among these, due to the quantity and of fines produced (about 1,800 tons per month) and the interest of mortar producers, was chosen the use of fine solids by a mortar factory under patent licensing from CETEM and INT. Now, a mortar plant is being built near the stone production sites, using that technology, as agreed between CETEM, INT and the company. The simplicity of the process and its use by more than 45 stone saw units rendered to the technical team two important national prizes, the 2005 Finep Innovation Prize, for the second place among more than 200 other projects competitors and the 2006 Furnas Blue Gold Prize, second place for Public Institutions Best Practices for Water Resources Management.

In the Cariri limestone APL, a complex situation was established since very poor agricultural workers, to complement their incomes, also started exploiting the limestone quarries (Figure 4). They produce tiles for building coverings from the sedimentary rock and/or make lime from the crystalline rock, in very rudimentary ways.

But there is an important constraint since the site is one of the more important fossils deposit in the world, from the Cretaceous Era, what makes artisanal mining unacceptable by most paleontologists. Fossils are also a federal property although many people are smuggling samples. To address some of those issues, stakeholders have worked together and recently obtained from the government an easy formal licensing for artisanal miners that allows them to keep their areas and go on with their production. They are also having support to improve quarries exploitation and will receive new machines to make “cut to size” tiles and other products that will be used by most of the miners, in a cooperative way.

Regarding their wastes, something about 2,5 Million tons of limestone are accumulated, mainly at rivers margins. These will be removed and used by a cement plant that has made and agreement with the producers in order to recover the impacted areas. Other wastes such as those left in the mines can have many industrial applications, as studies that are being carried out show. Limestones of that region are high-grade calcium carbonate materials with few contaminants, so can be useful for a broad range of industries. A similar type of water treatment units as the ones used in Santo Antonio de Pádua will be installed to recycle the process water from the cutting facilities. And here, also, the producers have used their creativity to use the wastes to make walls, mortar, furniture and also handicraft products (Figure 5).

Conclusions

For CETEM and its technical team the mining clusters support projects are being a very exciting opportunity to transfer adequate knowledge to mining communities that for many years were excluded from all types of government technological programs. This positive change is proving that with suitable help most of artisanal miners may develop their own operations in a much more sustainable way.

Organization name: Centro de Tecnologia Mineral-CETEM
Street address: Av. Pedro Calmon, 900 – Cidade Universitária
City: Rio de Janeiro
Postal code/ZIP: 21941-508
Country: Brazil
E-mail: cpeiter@cetem.gov.br
Web: http://www.cetem.gov.br/