Greg Eaton & Associates Pty. Ltd.

XTALTITE^® Waste Forms    
Toxic Waste Disposal    ---    Nuclear Waste Disposal

THE TECHNOLOGY

See US Patent  as a PDF   as a WORD DOC

Xtaltite® waste forms are artificial rocks which can immobilise toxic heavy metals and keep them from comtaminating the environment for periods measured in geological time scales.

The Xtaltite® product (pronounced crystal-tight) is the trade name for a generic technology, which is a family of synthetic rocks (or polyphase ceramics), which naturally incorporate toxic waste elements into the actual crystal lattice of the mineral, in order to consolidate, immobilise and permanently isolate, a wide range of toxic inorganic waste products (hence the name, Xtaltite®).

The design of Xtaltite wasteforms are such that they exploit and improve upon the insolubility of naturally occurring minerals. Heavy metal wastes, as well as being highly toxic, are fundamental elements and therefore cannot be destroyed. To render them safe, they must then be isolated from the environment in one way or another. They are produced in considerable volumes, often at remote locations where their effect, if allowed to pollute the environment, can be devastating.

Polyphase ceramics like the Xtaltite® wasteform, provide a most effective method of immobilising heavy metals prior to ultimate disposal. The Xtaltite® process has been demonstrated successfully in the laboratory and in small batch plants, and is proven capable of immobilising arsenic, lead, mercury, thallium, cadmium and antimony, (and in the presence of iron and sulphur) and has been shown to be able to be configured to immobilise other metals and metalloids including lanthanides and actinides.

Xtaltite® wasteforms can routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and are suitable for fabrication in using relatively simple technology. Experiments show that arsenic and antimony bearing smelter wastes can effectively be immobilised in the Xtaltite® form. Weight loadings of over 50% toxic oxides have been achieved in these experiments using actual waste material from a base metal smelter, achieving ground water leach rates orders of magnitude better than other methods. Similar results have been achieved with other toxic elemental waste and these are the subject of many published international papers on the Xtaltite® process.

Meets International Guidelines
Combined with a cement slurry, The Xtaltite® wasteform becomes an easily handled and safely transported product that meets all international guidelines for toxic waste disposal, including the TCLP tests. Waste loadings of 30% or more (toxic oxides) can easily be achieved using this method. The ability to produce viable Xtaltite® product in the presence of iron and sulphur also allows flexibility in pre-processing of any waste containing such elements, (most sulphide ore smelting waste).

Current Status
Patents for Xtaltite have been granted in many countries and are in the final stages of examination in remaining countries. The research has shown that the technology is at a mature stage where the next step is either a pilot plant or a pilot followed by a full scale plant. The company, by itself, is not able to fund this next stage.

The Need
Many industrial and mining operations yield voluminous quantities of toxic inorganic wastes. For example, base and precious metal plants in Australia contribute about 10,000 tons per year to a growing stockpile of highly toxic arsenic trioxide. (antimony oxides are equally as dangerous .) At least as much is allowed to escape to the environment, "when the wind blows in the right direction". This practice, however, will not continue for much longer without EPA intervention. Large quantities of other toxic metal oxides such as mercury, cadmium, thallium antimony and lead are also produced in the waste streams of smelting and mineral processing operations throughout the world. Presently, there are no established technologies for permanently disposing of such wastes in a manner which is acceptable to both industry and environmental protection authorities.

The Concept
A promising approach to the toxic element problem is to prepare synthetic analogues of minerals which naturally contain high concentrations of the waste species and are known to be only slightly soluble. This method has been extensively investigated for the immobilisation of high level nuclear waste, which can be regarded as an elaborate toxic inorganic waste, that displays the added complexity of being radioactive. The well publicised 'Synroc' is based on the principle of synthetic mineral immobilisation. Xtaltite Corporation have developed a newer method of synthetic mineralisation specifically tailored to the stabilisation of heavy metal wastes, and taking the synthetic mineral analogue further by modifying the chemistry to become even more insoluble. This new technology is known by the trade name the 'Xtaltite®' (pronounced crystal-tight) process and is produced under such differing conditions from synroc that it resembles synroc only in the fact that it is also a synthetic "rock".

Successful exploitation of such procedures requires that care be taken to select minerals which are;

• Easily and inexpensively prepared,
• Capable of high waste loading, and
• Able to be safely transported,
• Able to be permanently stored in a repository and remain stable there, under all environmental conditions placed upon such a repository.

The Xtaltite® process does just that.

Terminology
The terminology used to describe waste immobilisation requires some explanation if confusion is to be avoided. In particular, it should be emphasised that we are dealing with waste incorporation, rather than encapsulation. The former implies direct substitution of waste elements into the crystal lattice of a host mineral, while the latter describes the physical isolation (enclosure) of waste within a matrix of one kind or another. Of these two types of immobilisation, it is incorporation which is preferred, as it results in higher waste loading and a waste form whose behaviour is more guaranteed in a variety of environments even if primary isolation is lost.   Xtaltite® is a prime example of incorporation and cement is an example of encapsulation.

Advantages

	Key advantages of Xtaltite® waste forms include:	Xtaltite® Crystal Structure
	A volume effective, high waste loaded (>35wt%) ceramic
	Avoids the formation of secondary waste streams (by volatilisation, etc.)
	Stability over geological time scales
	Cost effective one-off processing and disposal costs. (set and forget)

Further information can be obtained through Greg Eaton & Associates, after suitable non-diclosure agreements are signed.
Requests can be emailed or phoned, faxed or posted to the above at the addresses on the home page.

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Revised Nov 12, 2003 .