Properties of Solid Wastes

In order to successfully study the environmental impact assessment and chemodynamics (fate and transport) of leachates from sohd waste materials that are used as in highway construction and repair applications, it is very important to comprehensively study the different physical and chemical properties specific for each waste material. The following is a summary of these properties. 

Fluorogypsum - Fluorogypsum is generated during the production of hydrofluoric acid from fluorspar (a mineral composed of calcium fluoride) and sulfuric acid 

Phosphogypsum - Phosphogypsum is a solid by-product of phosphoric acid production 

---

Properties of Solid Wastes Information on the properties of solid wastes is important in evaluating alternative equipment needs, systems, and management programs and plans. 

Particle size. The material handling properties of solid wastes are dependent upon particle size. This appfies as well to feed preparation and air pollution control which are affected by solid-waste particle size and cohesiveness. For wastes such as bulk soils, the amount of fines (from clay and silt) is critical for system design. Cohesiveness, which varies with moisture content, is important for Din and conveyor design. 

Table 10.7 Properties of solid waste products In the HT furnace...

H. Alter and J. J. Duim, Jr., Solid Waste Conversion to Energy Current European and U.S. Practices, Marcel Dekker, Inc., New York, 1980, Chapt. 5 H. Alter andj. A. CampbeU, in J. L. Jones and S. B. Radding, eds.. The Preparation and Properties ofDensified Refuse-Derived Fuel, Thermal Conversion of Solid Wastes andBiomass, American Chemical Society, Washington, D.C., 1980, pp. 127—142. 

Types of Solid Wastes The term solid wastes is aU-inchisive and encompasses all sources, types of classifications, compositions, and properties. As a basis for subsequent discussions, it will be helpful to define the various types of solid wastes that are generated. It is important to note that the definitions of solid-waste terms and the classifications vary greatly in prac tice and in literature. Consequently, the use of published data requires considerable care, judgment, and common sense. The following definitions are intended to serve as a guide. 

Comparable fuels. In order to promote the recycling of materials with high fuel values, certain materials that are burned as fuels are excluded from the definition of solid waste, provided that they meet certain specifications (i.e., are of a certain degree of purity). This is to ensure that the material does not exceed certain levels of toxic constituents and physical properties that might impede burning. Materials that meet this specification are considered comparable to pure or virgin fuels. 

Preliminary assessment of the potential hazard of solid waste (intrinsic chemical and toxicological properties)... 

It is highly preferable to use standard methods for sampling and storage (Lapa et al., 2002b) and conditioning (EN 12457-1 to 4, 2002) of solid wastes. It is also important to know, before any leaching experiments are conducted, relevant properties of the waste, such as ... 

A related area of research would include efforts to reduce the water requirements of flue gas treatment systems. This would be especially important to the wet throwaway systems most commonly used today. Research to improve the dewatering properties of scrubber sludge could be combined with the development of techniques to separate spent and unused sorbent, thus reducing both water and sorbent consumption while also reducing the volume and mass of solid waste to be handled. The use of waste or recycled water in flue gas treatment systems would also reduce water needs. Improved sludge stabilization methods that also remove water could also lower costs associated with both waste disposal and water consumption. 

The analytical protocols used to characterize hazardous wastes are primarily the EPA-approved methodologies found in their publication Test Methods for the Evaluation of Solid Waste, Physical/Chemical Methods, SW-846. Because these methodologies are a part of the waste analysis plan and the feed-stream analysis plan, they are required by the facility s RCRA permit. In the case of the feedstream analysis plan and the LDRs, adherence is required to meet specific regulatory requirements. Occasionally, DuPont will analyze streams for hazardous constituents or properties other than those required under the permit or regulations in order to address a specific issue (e.g., to determine if the stream can be recycled). Analyses like these should be considered not as an industrial best practice but only as an internal planning aid. 

Chemical Composition Information on the chemical composition of solid wastes is important in evaluating alternative processing and recovery options. If solid wastes are to be used as fuel, the six most important properties to be known are 1. Proximate analysis a. Moisture (loss at 105°C for 1 h)... 

Densification of solid wastes and biomass to produce solid fuels with more desirable physical properties is the subject of the fourth section. 

In contrast to minerals, the size-reduction process of solid wastes is relatively simple, as they are mostly composed of liberated materials. Also, the physical properties and mechanical characteristics of solid waste, which determine the... 

---