Leaching batch

Ores of gold, uranium and other metals are often batch-leached in Pachua tanks which are described in Section 10.3.4. 

Batch tests (i. e., tests on individual waste materials) are conducted with the provided solid suspensions (e.g., soils such as Woodburn, Sagehill, and Olyic, as well as two bottom sediment samples) prepared with previously air-dried solids (i. e., soils and bottom sediments), ground to a uniform powdery texture for mixing with the eluates from the 24-h batch leaching test of the different SWMs/COMs. The concentrations of eluates in solution were designed to evaluate the capability of different environmental solids to adsorb available contaminants. The solid particles were fully dispersed with the aqueous phase to achieve complete adsorption. Common practice is to use a solid solution ratio of 1 g 4 ml [ 1 ], together with proper tumbling of the samples at a constant temperature (e.g., at least 24 h in a constant temperature environment of 20°C). 

A sorption isotherm is completed for each solid particle type and SWMs/ COMs. A range of solid to solution concentrations (i.e., solid solution) was chosen for each solid phase and waste material leachate (e.g., 50-250 mg/l),with about five data points per range. All control and test samples were performed in duplicate. The solution used in the isotherms was prepared by a 24-h batch leaching experiment with the solid test material and distilled water. The material controls consisted of the test material leachate without the solid phase particles. Chemical analyses, expressed either as TOC or as individual organic compound (e.g., aliphatic and aromatic compounds) concentrations relative to the organic carbon content of the SWM/COM, revealed the actual concentrations of various organic constituents in the leachates. Solid phase controls were also prepared for each of the test soils/sediments in order to determine the concentrations of the constituents leached from the solid phase alone. 

Batch leaching tests, conducted for different types of waste materials, resulted in data that were modeled as shown in Eq. (94) ... 

Fig. 9a, b. Dynamic batch leaching experiment data for various solid waste material leachates a before modeling b after modeling... 

The Pacific Northwest National Laboratories estimated that the total cost estimate for batch leaching of contaminated soils is 30 to 500 per ton of treated soil and for heap leaching of contaminated soils is 10 to 150 per ton of treated soil. These costs include excavation, capital, and operating and maintenance costs. This estimate is based on costs for leaching of precious metals from ores in the mining industry (D18769D, p. 5). 

Batch leaching tests. The results of batch leaching with deionized water using the UK fly ashes from Drax and Meaford power stations are shown in Table 3. Three different fly ash samples were used in the study Drax fresh,... 

Batch leaching tests are generally taken as an initial step to evaluate toxicity of the ashes because the batch tests represent the best leaching conditions and generate the highest quantity of leachates (Benito et al. 2001). Serial batch leaching tests also often successfully simulate ash pond conditions (Praharaj et al. 2002), whereas the column leaching tests simulate dry ash disposal (Benito et al. 2001). 

Stook, K., Tolaymat, T., Ward, M. et al. (2005) Relative leaching and aquatic toxicity of pressure-treated wood products using batch leaching tests. Environmental Science and Technology, 39(1), 155-63. 

Leaching The dissolution and extraction of chemical species from solid samples by water, acids, bases, organic solvents, salt solutions, or other liquids (compare with batch leaching, column leaching, sequential batch leaching, serial batch leaching, and leaching test). 

Sequential batch leaching A batch leaching test where a solid sample is leached in successive volumes of different types of leaching solutions (compare with serial batch leaching, leaching test, column leaching, and batch leaching). 

WASTOXHAS was developed for assessing leaching hazardous impact of wastes in laboratory and field situations. It is a part of a tiered approach (Fig. 1). It assumes that classical batch leaching tests (see for example Sahuquillo et al., 2003), followed by application of relevant bioassays, have been initially undertaken for i) deciding to continue ecotoxic hazard assessment and ii) selecting adequate and sensitive bioassays. It can be eventually followed by a more complex and elaborate hazard assessment scheme based on microcosms or mesocosms. ... 

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