AU6128500A - A method of solidifying, waterproofing, fire proofing, hazardous, chemical, nuclear and industrial waste - Google Patents

Description

AUSTRAL IA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT A METHOD OF ,SOLIDIFYING,WATERPROOFING,F IRE PROOFING, HAZARDOUS CHEMI CAL ,NUCL EAR AND INDUSTRI AL WASTES.a a.

a a a a The following statement is a full description of this invention, including the best method of per-forming it known to me.

A METHOD OF SOLIDIFYING, WATERPROOFING, FIRE PROOFING, HAZARDOUS, CHEMICAL, NUCLEAR AND INDUSTRIAL WASTES- The present invention relates to the creation of a Dolomitic Cementatious Binder Composition by the crushing grinding and controlled partial calcination of selected Dolomitic rocks to create a fine Dolomitic powder.

The addition to the Dolomitic powder of measured quantities of selected organic and inorganic materials to create a 10 cementatious binder and encapsulation composition.

*A vast range of differing organic and inorganic Industrial Chemical and Nuclear waste fillers can be mixed with the Cementatious Binder Composition to manufacture by pressing, holding, extrusion, forming, gunning or plastering to create 15 solidified fire resistant and water resistant products which can be easily stored in suitable repositories for long term protection of the environment.

Any type of water such as sea water and the like can be used as a mixing agent to create a cementatious hardening or set." *20 The best known and widely used inorganic cementatious material is portland cement, used for preparing conventional concrete, among other draw backs concrete shows a high weight per unit of volume. It will not permanently bind organic fillers and its use is limited to the nature of mineral fillers.

For instance concrete will not bind a filler containing top S* soil and clay. The water for mixing portland cement must be chemically clean i.e substantially free of salts and acids which if present will unfavourably affect the setting of the concrete. Rocks sand and gravel used as fillers for portland cement concrete must be "washed" and free of salts, humus, clay and certain acids. The use of sea water for producing portland cement concrete is out of the question.

There also exist certain special cements such as magnesium oxychloride and oxysulphate the "Sorel" type cements which will readily and firmly combine with organic filler materials such as saw dust, wood shavings, straw etc.

Sorel cements have not fulfilled the hopes of their inventors because of several practical draw backs not the least of which are their brittleness, porosity and low shelf life.

It is one object of the present invention to provide a novel and highly valuable cementatious binder composition which will bind any type of organic or inorganic filler materials without complicated and expensive manufacturing procedures.

The novel binder composition according to this invention can be readily used like portland cement by simply mixing a single powder with fillers and water to obtain a set or hardness.

In addition this novel cement is not affected by variations in the purity of the slurrying water so that even sea water can be used- Another object of this invention, is to provide a cementatious binder composition which exhibits no undesirable porosity, no detrimental porosity or brittleness, even when large amounts 10 of organic filler are used.

Another object of this invention, is to provide a cementatious which is a blended mechanical mixture of dried and calcined compounds, ground and pulverised, which in the absence of water can be stored indefinitely.

15 A further object of this invention is to provide a binder composition which when mixed with combustible and non combustible filler material, will produce substantial non flammable solidified and water resistant waste product encapsulation medium.

The Dolomitic cementatious binder composition created by the :present invention consists in the main of selectively treated minerals found in the common rock Dolomite.

These minerals are Calcium Carbonate (CaC03) and Magnesium Carbonate (MgC03) which are the two natural minerals found in 25 the ore Dolomite.

A true Dolomite is one where Calcium Carbonate (CaC03) and Magnesium Carbonate (MgC03) represents at least 70% of the weight of the ore. Dolomites contain impurities of various differing types however as a general rule Dolomites contain small proportions of Alumina's,Feric's and Silica's.

Many Dolomite deposits are located adjacent to ancient clay beds and are contaminated with clays.

Many deposits of ore having various percentages of Calcium Carbonate (CaC03) and Magnesium Carbonate (MgC03) are loosely called Dolomites which is not strictly or technically correct.

A Dolomite deposit containing 65% Calcium Carbonate (CaC03) and 30% Magnesium Carbonate (MgC03) is called a low Magnesium Dolomite, conversely a Dolomite deposit containing Magnesium Carbonate (MgC03) and 30% Calcium Carbonate (CaC03) is called a high Magnesium Dolomite.

The calcination of Dolomite rocks at around 1500"c to create Calcium Oxide and Magnesium Oxide for use as a refractory material is well known.

During Calcination Calcium Carbonate will lose 44% of its weight due to the loss of Carbon Dioxide (C02). Magnesium Carbonate will lose 52;19% of its weight due to the loss of C02 (CaCO3/MgC03 Heat C02 CaO/MgO).

Interestingly a Calcium Carbonate as a separate and common mineral (CaC03) or Limestone will calcine at much lower 10 temperature of between 1000'C 1100"C. Natural Magnesite or Magnesium Carbonate as a separate and common mineral will calcine at approximately 750'C in dry heat.

Any Dolomite or Dolomitic substance such as Calcium Carbonate (CaC03) or Magnesium Carbonate (MgC03) when calcined at a high temperature over a period of time sufficient to expel all of the entrained C02 will become dead burned Calcium Oxide (CaO) and Magnesia Oxide (MgO).

This invention does not rely upon the use of dead burned Calcium Oxide (CaO) or Magnesium Oxide (MgO).

20 Magnesium Carbonate or Magnesite (MgCO3) as separate mineral which has been calcined or heated to temperature or condition whereby only part of the entrained C02 is removed is called caustic Magnesia Oxide, i.e Caustic Magnesia is (MgO ?C02) The art of this invention makes use of, as a necessary ingredient, Caustic Magnesia Oxide contained within a partially calcined Dolomite or as a separate commercially available Caustic Magnesia Oxide (MgO ?C02) material.

Dolomite which has been crushed and ground to fine powder consisting of predominately 250 mesh material will give off C02 from the Magnesium Carbonate (MgC03) at a temperature as low as 450'C when exposed to an atmosphere of superheated steam at a controlled temperature pressure and velocity-.

The release of C02 from the Magnesium contained within a pre ground or powdered Dolomite becomes extremely rapid in the controlled atmosphere of super heated steam pressure and temperature desired degrees of calcination can occur in as little as 3 seconds.

A wide range of calcined Magnesium or Magnesite (MgCO#) with various degrees of calcination or Caustic Magnesia contents can be used with this invention.

The art of the current invention relates to the use of a partially calcined Dolomite whereby a controlled amount of C02 of between 2% and 60% by weight of the C02 contained within the Magnesium Carbonate is retained. (CaCO3/MgO 2% to C02).

The art of the current invention also relates to the use of a measured quantity of commercially available powdered Calcium Carbonate which is blended with a measured quantity of commercially available powdered Caustic Magnesia Oxide to create a Dolomitic powder.

A further example of the art of preparing a Dolomitic ore for use in this invention is demonstrated, when a low Magnesium Dolomite ore is to be used as a required ingredient.

10 For example a low Magnesium Dolomite ore containing Calcium Carbonate (CaC03) and 30% Magnesium Carbonate (MgC03) plus impurities is calcined so that the Magnesium converts to partially calcined Caustic Magnesia Oxide but preferably S" where between 2% and 60% of the original entrained C02 within 15 the Magnesium is retained. (CaCO3/MgO 2%-60% CO2) After calcination a quantity of powdered Caustic Magnesia Oxide as the previously described independent mineral is blended with the powdered partially calcined Dolomite so as oo to bring the total weight of combined Caustic Magnesia Oxide 20 to any predetermined weight of percentage of the total weight of the blended materials.

The art of this invention requires the blending of sufficient additional separate Caustic Magnesia Oxide to create a suitable cementatious Dolomitic composition for particular uses and encapsulation of selected end waste products.

This portion of the art can be varied to allow for the weight of added or blended Caustic Magnesia Oxide to represent from 2% of the weight of the Calcium Carbonate to 3 times the weight of the Calcium Carbonate.

Some binder compositions may require Magnesia rich blends of partially calcined Dolomite and Caustic Magnesia Oxide.

The example of the art called out in the previous example is followed to prepare any Dolomite ore having various amounts of Calcium Carbonate (CaC03) and Magnesium Carbonate (MgC03) as their basic content.

An additional example of the art is the blending of a measured quantity of powdered Calcium Carbonate (CaC03), with a measured quantity of powdered Caustic Magnesia Oxide (MgC03), which has been calcined so that between two percent and sixty percent of the weight of carbon Dioxide (CO2) originally contained in the Magnesium Carbonate or Magnesite (MgC03) is retained within the Caustic Magnesia Oxide (MgO to 2% C02).

All of the preceding information details the preferable method of preparation of Dolomitic materials for use in the cementatious binder composition- The art of this invention calls for the additional blending of regulated quantities of powdered inorganic and organic materials to the powdered calcined Dolomitic powders and powdered blended Dolomitic materials as described herein- The art of this invention requires the addition of between and 10% of commercially available Alumina Sulphate A12(S04)3 and between :05% and 5% of commercially available Citric Acid or Lemon Acid (C6H807) both of which substances have been pre ground and powdered to minus 250 mesh.

The amount of Alumina Sulphate and Citric Acid will be varied to suit the manufacturing requirement of the type of end 15 product being manufactured- The Alumina Sulphate used is a powdered commercial grade having a hydration figure of 14 (:14 H20) and if another Alumina Sulphate is used having a higher or lower hydration figure then the total weight used is adjusted accordingly.

20 A further example of the art of this invention is to add to the prepared Dolomitic Powder a quantity of water to which has been added 5% by weight of the water Sulphuric Acid i (H2S04) as a normally commercially available pure form of the acid.