Solids recovery, definition

Wettability of a solid surface definition and assessment The concept of wettability of a solid by a liquid is directly related to the wetting processes. This concept is specially useful in the fields of detergency, lubrication or enhanced oil recovery. In the context of the oil industry, proposals were made by Briant and Cuiec (1972) for the experimental assessment of wettability, which was defined in terms of the thermodynamic affinity of a solid surface for a liquid. 

As was explained in chapter 1, solid-liquid separation is often assessed by considering the solids recovery and the moismre content of the recovered solids simultaneously, with their relative importance varying with application. If a single parameter which combines both of these criteria together is required, some efficiency definitions originally proposed for powder classification may be used, as below. In this case it is advantageous to redefine the description of the three streams involved as follows ... 

Pulping liquors. Pulping liquor, also called black liquor, is a corrosive material used to dissolve wood chips for the manufacturing of paper and other materials. To promote waste minimization and recycling, U.S. EPA excluded pulping liquors from the definition of solid waste if they are reclaimed in a recovery furnace and then reused in the pulping process. If the liquors are recycled in another way, or are accumulated speculatively, they are not excluded. 

Splash condenser dross residue. The treatment of steel production pollution control sludge generates a zinc-laden residue, called dross. This material, generated from a splash condenser in a high-temperature metal recovery process, is known as a splash condenser dross residue. Because this material contains 50 to 60% zinc, it is often reclaimed, reused, or processed as a valuable recyclable material. Facilities commonly handle this material as a valuable commodity by managing it in a way that is protective of human health and the environment, so U.S. EPA excluded this residue from the definition of solid waste. 

Processed scrap metal. Scrap metal includes, but is not limited to, pipes, containers, equipment, wire, and other metal items that are no longer of use. To facilitate recycling, scrap metal that has been processed to make it easier to handle or transport and is sent for metals recovery is excluded from the definition of solid waste. Unprocessed scrap metal is still eligible for an exemption from hazardous waste regulation when recycled. 

The Resource Conservation and Recovery Act (RCRA) was enacted in 1976 and was revised substantially by the Hazardous and Solid Waste Amendment (HSWA) of 1984 (40 CFR pts. 260-280). The RCRA regulates the management of solid wastes that are hazardous. The definition of solid wastes in these regulations generally encompasses all discarded materials (including solid, liquid, semisolid, and contained gaseous materials) and many secondary materials (e.g., spent solvents, byproducts) that are recycled or reused rather than discarded [3]. Products such as commercial pesticides are not ordinarily solid wastes, but they become solid wastes if and when they are discarded or stored, treated, or transported prior to such disposal. 

Due to the particular effects of the microwaves on matter (namely dipole rotation and ionic conductance), heating of the section, including its core, occurs instantaneously, resulting in rapid breakdown of protein crosslinkages. Furthermore, the extraction and recovery of a solute from a solid matrix with microwave heating is routinely obtained in the field of analytical chemistry (Camel, 2001). However, a definite, full explanation of the effects of microwave heating on the molecular aspect of antigen retrieval is awaited. 

Unlike aqueous samples, spike recovery for soil and solid wastes often does not require ary correction to be made in the volume of spike solution. Because the analysis of all soil and solid matrice requires that the analyte in the solid sample be extracted into a definite volume of solvent, there is no need to make ary volume or mass correction for the spike in solution added. This is shown in Example 6. 

Another type of an action level is a regulatory definition of hazardous waste that allows identifying hazardous materials and determining the waste disposal alternatives. The Resource Conservation and Recovery Act (RCRA), which is the law for disposal of solid and hazardous wastes, regulates hazardous waste in its Subtitle C. The RCRA, promulgated in 1976 and amended in 1984, today primarily focuses on regulating the operation of hazardous waste sites and on land disposal activities. 

In all of these attempts at a definition or classification of petroleum, it must be remembered that petroleum exhibits wide variations in composition and properties, and these variations not only occur in petroleum from different fields but may also be manifested in petroleum taken from different production depths in the same well. The mixture of hydrocarbons is highly complex. Paraffinic, naphthenic, and aromatic structures can occur in the same molecule, and the complexity increases with boiling range of the petroleum fraction. In addition, petroleum varies in physical appearance from a light-colored liquid to the more viscous heavy oil. The near-solid or solid bitumen that occurs in tar sand deposits is different from petroleum and heavy oil, as evidenced by the respective methods of recovery (Speight, 1999,2000). 

Two usual definitions of partial efficiency are the "rejection efficiency" and the "acceptance efficiency" or recovery index. The rejection efficiency, relevant in classification of powders, is considered as the mass of coarse product greater than the cut size (the limiting size dividing a particle size distribution into fines and coarse fractions) related to the mass of feed solids greater than the same cut size. According to this, in Equation 10.21 Xj would represent the cut size (X50) and X2 would be the maximum particle size in the feed. The rejection efficiency E, can be expressed as a function of cumulative oversize (coarse) percentage and the cumulative percentage of coarse fraction in the feed F, as... 

The latter form of Newton efficiency shows the physical significance because it is clearly the mass recovery of the solids Ej minus the undesirable recovery of liquid, both in the underflow. This efficiency definition was selected as the best available by Tengbergen but, more recently, Ogawa et al have pointed out that it gives uneven sensitivity to small changes in the mass fractions of solids in either the underflow or in the overflow (as can be seen from equation 3.46). In order to make the sensitivity more uniform over the whole range of possible values of yu and yo, Ogawa et al. derived... 

Another development was sponsored by Fryma-Maschinenbau GmbH, BASF and Westfaha Separator AG . This centrifuge was designed to produce fine product which has no particles above a preselected size (e.g. 4 microns) present and in that it succeeded. However, it did that at a cost of extremely low fine product yield less than 1% of solids was recovered as fine product yet there was 20% present in the feed The machine run with the split ratio R (see section 3.4.1 for the definition) 70.8% which led to the coarse recovery of 99.2%. The particle size distributions presented in the paper did not allow grade efficiency evaluation because they were not in mass balance. 

Circuit boards receive a special exemption from federal hazardous waste rules. Whole used circuit boards meet the definition of spent materials but also meet the definition of scrap metal. EPA exempts recycled whole used circuit boards from hazardous waste regulation. EPA also excludes shredded circuit boards from the definition of solid waste if they are containerized before recovery. Shredded circuit boards cannot contain mercury switches, mercury relays, nickel cadmium batteries, or lithium batteries. 

All nonproduct hazardous outputs into all environmental media, even though they may be within permitted or licensed limits. This is much broader than the legal definition of hazardous solid waste in the Resource Conversation and Recovery Act, its amendments, and subsequent regulations. Hazardous refers to harm to human health or the environment as is broader than the term toxicity. For example, wastes that are hazardous because of their corrosive, flammability, explosiveness, or infectiousness are not normally considered toxic. [p. 31]... 

Defining what constitutes a hazardous waste requires consideration of legal and scientific factors. The basic definitions used in this chapter are derived from (a) the Resource Conservation and Recovery Act (RCRA), as amended by the Hazardous and Solid Waste Amendments (HSWA), and (b) the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA). These definitions are given below. 

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