Evaluation of ettringite-related swelling mechanisms for treated chromite ore processing residue.

Accelerated one-dimensional unconfined swell tests were conducted for ferrous sulfate chromite ore processing residue (COPR) field-treated samples. The field-treated samples were subjected to wet and dry cycles over 100 days to accelerate the lithification of the samples. Parallel laboratory experiments were performed to investigate the effects of mineralogy on COPR swell under controlled conditions.

Recurrent wheezing is associated with intestinal protozoan infections in Warao Amerindian children in Venezuela: a cross-sectional survey.

Background: While in developed countries the prevalence of allergic diseases is rising, inflammatory diseases are relatively uncommon in rural developing areas. High prevalence rates of helminth and protozoan infections are commonly found in children living in rural settings and several studies suggest an inverse association between helminth infections and allergies. No studies investigating the relationship between parasitic infections and atopic diseases in rural children of developing countries under the age of 2 years have been published so far.

Swelling related to ettringite crystal formation in chromite ore processing residue.

Several million tons of Chromite Ore Processing Residue (COPR) were deposited at two sites in New Jersey and Maryland, USA, and over time they exhibited extensive heaving phenomena. Ettringite, a needle-shaped mineral and an expansive mineral commonly recognized in the literature concerning cement- and soil, has been identified extensively in numerous COPR samples collected from these sites. It was therefore believed that ettringite formation and its crystal growth are strongly associated with COPR heaving.

Long-term treatment issues with chromite ore processing residue (COPR): Cr(6+) reduction and heave.

A pugmill treatability study was conducted to remediate chromite ore processing residue (COPR) using ferrous sulfate heptahydrate (FeSO(4) x 7H(2)O) as a reductant. Two different types of COPR, with respect to particle size and mineralogy, were tested in this study. Two different stoichiometric ratios of FeSO(4) x 7H(2)O to Cr(6+) (5x and 8x) were applied to reduce Cr(6+) to Cr(3+).