Moon Miners' Manifesto

#23 March 1989

Tailings

MMM 23-5 to 23-6

TAILINGS

by Peter Kokh

TAILINGS: (TAY'lings) the residue of any process such as mining. The leavings.

Anybody who has ever visited a mining area, has seen the large talus slopes or mounds of pea to acorn sized rubble of unwanted material that announce the approaches to mine openings. This is the chewed up and spit out host material in which the desired ore vein was embedded and which had to be removed to get at the prize. Tailings also refer to the the accumulated leavings after the sought after metal is extracted from its ore. As a rule, the volume of tailings is enormously greater than that of the extracted ore. This is especially so with the noble metals, gold, silver, platinum, and copper. In the case of copper, for example, the volume of tailings to metal is typically 100:1.

To the environmentalist without imagination, tailings are a terrible eyesore. To the rare creative environmentalist and would-be entrepreneur, they are instead a vast untapped resource just begging to be put to work.

What is so special about tailings that would justify such a bold statement? Simply this: tailings have already undergone a considerable amount of work. They have already been extracted from the mine site, and are already uniformly ground up into bite-sized pieces often of quite uniform composition. As such they are already preprocessed and represent a substantial energy investment that goes utterly wasted when they are allowed to just sit there scarring the landscape.

In much of the world where rich ore veins exist, paradoxically there is often a scarcity of the traditional building materials. True friends of the Earth would quit wasting time ranting and raving about scenic eyesores and spend their time diligently experimenting with these tailings to see what sort of building materials they could be turned into, putting to advantage the energy investment that has already been made. Alas, creatively enterprising environmentalists are about as common as woolly mammoths.

On the Moon, we will find soils richer in this element, soils richer in that element, but likely only in degrees and percentages. While prospecting for especially rich deposits of strategic materials will have its ups and downs, probably more of the latter, basic needs will be able to be met by surface mining of the loose 'topsoil' at almost any 'coastal' site, as such areas have access to both the higher aluminum and calcium rich highland soils and the iron and titanium rich basaltic (lava flow) mare soils of the lunar 'seas'. Among coastal sites, those that also have KREEP (potassium, rare earth elements, phosphorus) deposits will have a special advantage.

The ore company, let's call it Ore Galore Inc. or OGI, will first separate the loose lunar soil or fines into fractions by electrostatic and mechanical means. These fractions will then go to various processing facilities dedicated to the production of oxygen, iron, aluminum, titanium, magnesium, glass and glass composites, lunar cement, etc. At the end of each processing line there will be leftover material, tailings. These tailings will often be as rich as the material that undergoes final processing, but will be discarded because they cannot be processed as easily or economically.

Now the principal lunar industries will be concerned with the two most urgent needs, export to pay the bills, and basic shelter: habitat construction. Frills, such as finishing materials, interior (i.e. secondary) building products, furnishings, etc., will have a much lower priority for OGI. The lunar entrepreneur, experimenting in free time if necessary, will have on hand any number of piles of tailings, each probably with some characteristic gross composition resulting from extraction of the different desired elements. The tailings at the Glax™ (glass-glass-composites) plant will differ from those of the Iron plant or the cement plant etc. We could just leave them there, but considerable energy will then be wasted, the energy which has gone into their sorting and prior scavenging for adsorbed gasses. But the real opportunity that suggests itself is to turn these tailings into various secondary building products meant for finishing and furnishing habitat interiors at the settlers' labor-intensive leisure. These can include decorative panels (glax), tiles for walls and floors, ceramic and glass home wares, special glax compositions for distinctive furniture etc. OGI cannot be bothered with sourcing for such needs but will be only to happy to provide tailings for the taking. Simple opportunism, neighborly and environmentally aware to boot.

Consider the tile-maker. The tailings from the glax plant, when melted and cast, may yield tiles of one characteristic color pattern (very likely variegated), while those from the iron plant may yield another. Aha! variety! interest! choice! - the stuff to whet consumer appetites by allowing personalization and customizing of habitat interiors at leisure once the cookie-cutter pressurized habitat shells have been appropriately mass-produced in the least possible labor-intensive manner. In these various tailing piles lie the seed of incipient lunar entrepreneurialism and small business free enterprise.

The environment-respecting aspect of such products might be advantageously marketed as such to the aware consumer. For example, tiles made from cast tailings might be called 'slaks' (from 'slag').

There will be an especially great demand for coloring agents -- on the Moon that will mean metal oxides exclusively rather than the complex organic dyes derived from coal tars etc., that we are used to -- coloring agents for ceramic glazes, stained glass, and special inorganic 'paints' (probably using waterglass, hydrated sodium silicate, as a base*) etc. Some tailing piles may be richer sources of one such colorant or the other. No doubt some sources may be prized for yielding products of special textures or other desirable properties.

On the one hand, because of the urgent priorities imposed by the need to justify the infant lunar settlement economically, basic end products such as iron, export quality glax, etc. could well be off limits to the home-improvement product manufacturer. On the other hand, using raw unprocessed regolith or soil may yield only a quickly boring and unvaried product line, and further disturb the surface. Pre-differentiated tailings offer a handy and elegant solution.

There is perhaps no better single criterion by which to judge a society's environmental impact than the degree to which its material culture utilizes resources in proportion to their availability, On Earth, our record is abysmal, even amongst cultures which 'live off the land.' We still discard as unwanted too much material after investing precious energy to sort through it for some prized content. If tailings-based building products industries were pursued vigorously here on the home world, there would be far fewer shelterless people in the world, if any, and their homes could be more substantial and satisfying. All it takes is a few people with justified environmental concerns who are willing, to spend more effort in concrete solutions than in raising hell. Complaining is so cheap.

On the Moon, industries should be built up to utilize all the elements present in abundance: with oxygen, silicon, iron, aluminun, titanium, and magnesium, the eventual uses are obvious though requiring different degrees of sophistication. Calcium is the one very abundant element, especially in the highlands, that is most likely to go underutilized. Calcium, of course, is a major ingredient of cement, and Lunacrete, as investigators have begun to call it, is one of the most promising building materials for lunar installations, if and only if a cheap enough source of water, water-ice, or hydrogen can be located and accessed**. If not, the choices will be either to discard calcium with tailing piles being characteristically calcium-rich, or to accept the challenge of finding other ways to put it to use. Whitewash could be one of these.

A lunar administration granting licenses to enterprises might give tax or other incentives to those that are tailings based, to encourage opportunistic usage of material already extracted, rather than allowing additional square kilometers of lunar soil to be mined. This can be done simply by refusing license to mine or use unprocessed lunar soil to manufacture secondary products. Industries should be encouraged to form in a raw materials cascade in which one industry uses for its raw materials the discards of another, until the ultimate residue is minimal or nonexistent. Not only would such a material civilization have the highest standard of living at the lowest environmental impact, it would also use and reuse energy in the most efficient way. Combine this with recycling, and the ultimate test of a mature civilization is one that is without residue. That is a stubborn goal, so hard to realize that it may seem economic fantasy to some, but one nonetheless worth insistently striving for. The rewards will be great. But above all, on a world where so little is handed to us on a silver platter, only such total use of what we do mine may allow us to beat the economic odds stacked against our success.

Next time you pass a tailing-scaped mining site on some Earthbound highway, stop and take another look. There are fortunes to be made in this unwanted stuff, and preparing for Moon-appropriate industrial protocols while filling vast unmet needs here below might not be such a bad idea. Now if I were still a young man ....... -- Peter Kokh 2/89 MMM

* [We subsequently actually experimented with such "paints", producing the first Lunar-style painting in September, 1994]

** [Dr. T. D. Lin has since performed successful experiments using steam instead of liquid water, reporting on this work at ISDC '98.]

Contents of this issue of Moon Miners' Manifesto