Sequential leaching solutions

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). 

Figure 13. Composition of sequential leaching solutions in a 2 1 mixture of water and composite soil A...

The kinetics of dissolution of pure CaC03 and soil CaC03, as indicated by the volume of C02 released and Ca dissolved during extraction, are presented in Fig. 4.3. It shows that dissolution of both pure and soil CaC03 by the NaOAc-HOAc solutions at various pHs reached a plateau after two hours. This indicates that a certain acid dose reacts completely with the proper content of soil carbonate within two hours. Tessier et al. (1979) reported that after five hours of leaching sediments, there was no increase in the calcium concentration, thus indicating that it is unnecessary to allow 16 hours for extraction of the CARB fraction, as was originally done in this sequentially selective dissolution procedure. 

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). 

Understanding sulfate transport and retention dynamics in forest soils is a prerequisite in predicting S04 concentration in the soil solution and in lake and stream waters. In this study, forest soil samples from the Gardsjon catchments, Sweden, were used to study S04 transport in soil columns from the upper three soil horizons (E, Bs, and BC). The columns were leached using a sequential leaching technique. The input solutions were CaS04 equilibrated with forest floor material. Leaching behavior of S04 and concentration in the effluent were measured from columns from individual horizons. S04 was always retained in the Bs and BC horizons, while... 

In order to evaluate the maximum amount of metal that may be leached by urban sludge and the extracting action of different solutions on the same metal fraction, a future program based on a sequential extraction procedure on the same sludge sample must be carried out. 

The geochemical behaviour of Cs and Pu in Solway floodplain cores, collected from Southwick Water, south-west Scotland, has been studied by Allan et al. (1991) by employing a sequential leaching scheme (Cook et al., 1984 Livens Baxter, 1988b McDonald et al., 1990). This scheme incorporates solutions of calcium chloride (readily available sites), acetic acid (specific adsorption sites), tetra-sodium pyrophosphate (organically associated), ammonium oxalate/oxalic acid, (Fe and Mn secondary minerals), dilute nitric acid (dilute acid soluble sites) and nitric acid/ hydrofluoric acid (residual fraction). This technique has been subject to... 

It is also possible to pre-blend limonite and saprolite slurries. However as the examples in Table 4 demonstrate, recoveries fi om the sequential limonite followed by saprolite leach (JAL) are at least equivalent and arguably superior, while producing end solutions of lower acidity and iron content [28]. This has material implications for the quantity of limestone required for neutralization and equipment sizing for downstream solid-liquid separation and residue storage. 

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