Kinetics of heavy metals leaching from contaminated soils in metallurgical plants

Kinetics of Heavy Metals Leaching from Contaminated Soils in Metallurgical Plants Paolo Desogus , Pier Paolo Manca , Giampaolo Orrù Abstract The work aims to highlight the main parameters that affect the efficiency of the process of leaching of heavy metals from a natural soil taken from inside a metallurgical plant. The studies were conducted by laboratory tests and the results will allow identifying the fundamental choices for the applications of the technique of in situ soil flushing. The tested soil samples were mainly made by fine silica sand, with medium density. Their pollution was caused by waste of the metallurgy of lead and zinc released into the soil to transport by rainwater. Their depth ranges from 1 to 2 meters from ground the level from which they are separated by artificial strata composed of soil mixed with metallurgical solid waste. The layer of soil tested hosts an aquifer with a slow permeability, variable depth generally higher than 10m contaminated by heavy metals. The leaching experiments were conducted through the batch and column tests. Acid solutions (acetic. nitric. hydrochloric and sulfuric) were used as extracting agents. During the leaching tests, concentrations of analytics Zn, Pb, Cd, Cu, Mn and Al were verified. The results highlighted two aspects: (a) the conditions for which they get the best efficiency of leaching and (b) the laws of statistical correlation that describe the kinetics of reaction. The calculations performed have shown that the most efficient leaching agent was the CH3COOH and mainly the flow velocity of the leaching solution conditions the reaction kinetics in the column

The reuse of abandoned Acquaresi mine voids for storage of the Masua flotation tailings

Often in abandoned mine sites are present both underground voids produced by mining and the tailings of treatment plant. An interesting solution for the rehabilitation of the sites would be to place the tailings of the process in the underground mining voids, thus obtaining the reclamation of surface areas and the stabilization of abandoned voids to prevent the dangerous phenomena of subsidence. However, these operations require inert waste, which must not be source of pollution, and the choice of a water/solid optimum to ensure good conditions of pumpabilit

Fanghi di segagione della trachite per la produzione di laterizi

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Carta delle rocce ornamentali della Sardegna

The poster shows a collection of decorative stones extracted over the last fifty years in Sardinia. The term decorative stone is used generically to refer to all natural stones that can be used as decorative material, mainly for cladding and covering and secondarily in a structural role. The term ornamental stone is also used. The international industry term is dimension stones. Reflecting multiple geological events, the lithological Sardinian landscape has offered and still offers a remarkably wide range of possibilities for researching and gathering decorative stones, according to varying requirements, the main being chromaticism and workability, not forgetting other important characteristics such as hardness and durability. The survey in the Regional Plan of Mining Activities (Piano Regionale delle Attività Estrattive - P.R.A.E.) for the Autonomous Region of Sardinia (Regional Law 30/89) identified eight “Dimension stone producing areas”, each of which features quarries for petrographically homogeneous rock types: granite (4), limestone (1), volcanic rocks (2, basalt and ignimbrites), metamorphic rocks (1

Map of natural stones from Sardinia

The poster shows a collection of natural stones quarried for ornamental purposes in Sardinia (Italy) over the last fifty years. Its user-friendly map has been graded to school students level and can be used as a reference in public libraries. There are no previous publications showing a similarly wide range of Sardinian stones. The poster offers scientific information about lithology, quarrying sites, dimension stone producing areas, quarries of historical and/or archaeological interest, historical trend in quarries output, technical properties, stone surface workability and a glossar

An experiment to foster the study of pottery wheel-throwing speed

An experimental reproduction of wheel-manufactured pots using different speeds is presented in order to discuss the identification of manufacturing techniques in ancient pottery

Heavy metal leaching contaminated soils from a metallurgical plant

Laboratory tests were carried out to determine the primary parameters affecting the efficiency of the process of leaching heavy metals from natural soil collected inside a metallurgical plant in Italy. The soil samples tested consisted primarily of medium density, fine silica sand that had been contaminated with lead and zinc metallurgical wastes by percolating rainwater. Samples were obtained 1 to 2 m below ground level in an area where the surface consists of artificial strata composed of soil mixed with metallurgical solid waste. The soil layer tested hosts a low-permeability aquifer (at depths generally greater than 10 m below ground level) that is also contaminated by heavy metals. Batch leaching experiments were conducted using acid solutions (acetic, nitric, hydrochloric and sulphuric) as extracting agents. During leaching tests, concentrations of Zn, Pb, Cd, Cu, Mn and Al were monitored. Results indicate that the best leaching solution varies for all analytes and soil samples examined. Statistical analysis was used to identify correlations between efficiency and leaching rate