|Wisconsin Recovers "Cenospheres" from Coal Fly Ash|
|Sunday - January 29, 2012|
In a recent dispatch, now accessible on the West Virginia Coal Association's web site via the link:
Georgia Tech Recycles Coal Utilization Byproducts | Research & Development; and concerning: "United States Patent 8,057,594 - High Strength Pozzolan Foam Materials and Methods of Making Same; November, 2011; Assignee: Georgia Tech Research Corporation, Atlanta, GA; Abstract: The various embodiments of the present invention relate generally to high strength foam materials and methods of making the same. More particularly, various embodiments of the present invention relate to high strength foam materials comprising pozzolans, such as cenospheres derived from fly ash";
we made further report on how what are described by Georgia Tech as "strong and lightweight" construction "materials that are environmentally-friendly and can be manufactured economically", and, which can be produced using what are known as "Cenospheres"; in essence, tiny, hollow "bubbles" of vitrified silicate minerals extracted from Coal-fired power plant Fly Ash.
The Cenospheres are posited by Georgia Tech to be used in admixture with conventional Portland-type cement and concrete to form "high strength foam materials" that can be "molded" into such things as "building element"s, which, when incorporated into construction, provide multiple economies.
First, they displace some of, and lessen the demand for, the Portland cement itself, the making of which demands an immense amount of thermal energy, in addition to the energy expended in the mining and quarrying of the conventional raw materials.
Second, due to their lighter weight, building materials and elements containing Cenospheres require the expenditure of less energy in their handling and placement.
And, third, the hollow construction of Cenospheres imparts some additional thermal insulating capacity to the things in which they are incorporated.
Composed as they are of essentially the same minerals as the bulk of Coal Ash, Cenospheres are, as well, chemically reactive with regards to the other components of Portland cement, and, just like regular Coal Ash, become a strong, chemically-bound component of any concrete structure that contains them.
The value of Coal Ash as a performance-enhancing additive for Portland cement and as an aggregate for Portland cement concrete, as we've also been documenting, as, for one instance, in:
"United States Patent 4,256,504 - Fly Ash-based Cement; 1981; Assignee: The United States of America (as represented by the Secretary of the Interior); Abstract: A cement composition comprising a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the cement";
has been well-established. And, numerous entities across the nation, indeed, around the world, have devoted considerable effort into establishing the ways and means by which Coal Fly Ash can be reclaimed and prepared for utilization; as seen, for example, in our report of:
Wisconsin Cleans Ammonia from Coal Ash | Research & Development; concerning both: "United States Patent 6,755,901 - Ammonia Removal from Fly Ash; 2004; Inventors: Bruce Ramme, WI, et. al.; Assignee: Wisconsin Electric Power Company; Abstract: A method and apparatus for the application of heat to remove ammonia compounds from fly ash, thereby making the fly ash a marketable product is disclosed"; and,"United States Patent 6,945,179 - Ammonia Removal from Fly Ash; 2005;Inventors: Bruce Ramme, WI, et. al., Assignee: Wisconsin Electric Power Company; Abstract: An apparatus for the application of heat to remove ammonia compounds from fly ash is disclosed".
In point of fact, the Wisconsin Electric Power Company, as above, has, through their lead named inventor, Bruce Ramme, demonstrated a somewhat singular and commendable devotion to the development of technologies which would enable the profitable recycling of Coal Utilization Byproducts. And, we see herein that they have quite recently focused some attention on extracting and grading the valuable component of Coal Ash described and defined so well by, as we cited above, Georgia Tech University, i.e., Cenospheres.
Comment follows excerpts from the initial link in this dispatch to:
"United States Patent 8,074,804 - Separation of Cenospheres from Fly Ash
Date: December, 2011
Inventors: Bruce Ramme, et. al., WI
Assignee: Wisconsin Electric Power Company, Milwaukee
Abstract: Methods for increasing the amount of cenospheres in a fly ash sample are disclosed. The cenospheres are obtained in a dry state by using air as the "fluid" media for separation. In one version, the invention is a two step process, that is, screen by size followed by density separation such as in a fluidizing vertical column by density. In another version of the invention, the separation by density is followed by screening by size. Additional cycles can improve purity as defined by concentration of cenospheres.
Claims: A method for increasing the amount of cenospheres in a fly ash sample, the method comprising:
(a) providing an amount of fly ash having an initial percentage of cenospheres;
(b) separating the amount of fly ash into a first fraction of fly ash having particle sizes greater than a predetermined particle size and a second fraction of fly ash having particle sizes less than or equal to the predetermined particle size; and:
(c) separating the first fraction of fly ash or the second fraction of fly ash into a third fraction of fly ash having particle densities greater than a predetermined particle density and a fourth fraction of fly ash having particle densities less than or equal to the predetermined particle density such that the fourth fraction of fly ash has a percentage of cenospheres greater than the initial percentage ... .
Background and Field: This invention relates to a method for increasing the amount of cenospheres in a fly ash sample.
The process of burning coal in a boiler produces fly ash. Some of the recovered fly ash is commercially usable in concrete, concrete products, cement production, sewage sludge stabilization, pavement base materials, lightweight aggregate, reinforced plastics, and other miscellaneous purposes. The remaining fly ash must generally be disposed of by landfilling since it has no commercial value. It is well known that landfill space is rapidly dwindling in many regions and that the construction of new landfills is very costly. Therefore, much effort has been directed at finding uses for fly ash so that the fly ash does not need to be landfilled.
The composition of fly ash can vary depending on the composition of coal that generated the fly ash. Therefore, material specifications have been developed for fly ash that is to be used in specific applications. For example, fly ash that is used as a filler in concrete should meet the specifications described in American Society for Testing and Materials, "Standard Specification for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete", Designation: C 618. This ASTM specification indicates that fly ash particles are made largely of silicon dioxide, aluminum oxide and iron oxide. The particles in fly ash have different types of structures. Some particles in fly ash are solid. Other particles in fly ash are hollow and are called cenospheres. A cenosphere is a lightweight, inert, hollow sphere filled with inert air or gas. Cenospheres are hard and rigid, light, waterproof and insulative. Due to the hollow structure, cenospheres have lower density ... as compared to solid fly ash particles.
In the composite materials field, there is increasing interest in ultra light energy-absorbing materials and structures which incorporate hollow particles. Accordingly, cenospheres have been added to polymers and there is growing interest in incorporating them in metals. Fine and sized cenospheres can be sold at attractive prices to this segment of industry providing syntactic foams and cellular solids. In addition, there is a growing market for fine solid microspheres to produce reinforced polymers, metals and ceramics.
(The) known methods for recovering cenospheres from fly ash do not allow for recovery of cenospheres of controlled sizes and densities. As a result, the properties of polymeric composites including cenospheres have not been optimized due to lack of availability of cenospheres of controlled sizes and densities. Thus, there is a need for a method for recovering cenospheres from fly ash that has cementitious properties. There is also a need for a method for recovering cenospheres of narrow size ranges and densities from fly ash.
Summary: The need for an improved method for recovering cenospheres from fly ash is met by a method according to the invention. In the method, the weight or volume percentage of cenospheres in a fly ash sample is increased preferably providing a material of greater than 90% cenospheres.
This invention relates to a method in which the weight or volume percentage of cenospheres in a fly ash sample is increased preferably providing a material of nearly 100% cenospheres. The recovered cenospheres may be used to produce reinforced polymers, metals, ceramics, and other products."
Again, although not specified in their summary, Fly Ash Cenospheres can also be used as an additive for cement and concrete; and, when the fact that, as in our above citation of the US Government-owned:
"United States Patent 4,256,504 - Fly Ash-based Cement; 1981; Assignee: The United States of America (as represented by the Secretary of the Interior); Abstract: A cement composition comprising a high calcium-content fly ash";
the cement itself can be made from the remaining solid constituents of Coal Ash is taken into consideration, the potentials for use of solid Coal Utilization Byproducts become genuinely staggering.
And, since Coal Ash Cenospheres can also "be used to produce reinforced polymers", we remind you, that, as seen for one example, with more to follow, in:
Carbon Dioxide + Coal Fly Ash = Synthetic Lumber | Research & Development; concerning, in part: "United States Patent 5,371,183 - Preparation of Urethane from Polyamine and Carbon Dioxide; 1994; Assignee: Monsanto Company; Abstract: The present invention provides a process for preparing urethanes and carbonates from an amine or an alcohol (and) carbon dioxide";
some such "polymers" can be synthesized from, in part, Carbon Dioxide, the potentials for use of all of our Coal Utilization Byproducts, both solid and gaseous, becomes sort of mind boggling.
We will have more on the profitable recovery and use of Cenospheres, and the bulk of Coal Ash, as well, in reports to follow.
But, herein, their value as an industrial and commercial raw material is demonstrated by a public utility company of some substance, in Milwaukee, Wisconsin - not exactly in the heart of US Coal Country.
When, do you suppose, that genuine value of our Coal Utilization Byproducts will become publicly known, not just in US Coal Country, but, more importantly, in Washington, DC?