About 80% of the worlds' reserves for platinum group metals (PGMs) are in South Africa's Bushveld Igneous Complex. Processing of PGM involves comminution, flotation, smelting, converting, base metals refinery and precious metals refinery. Due to increasing chrome content in the feed and the challenges associated with operating high …

The Hongge mineral deposit in the Panzhihua-Xichang Area of China is the biggest vanadium bearing titanomagnetite, with titanomagnetite reserves of 3.55 billion tons [].It is also the largest chromium bearing deposit in China [].Vanadium, chromium and titanium are all important strategic metals and industrial raw materials, and the …

For the EDTA extraction, method detection limit (MDL) and method quantification limit (MQL) for total Cr in leather were 3.4 ppb and 11.2 ppb (μg of total Cr per L of extraction solution ...

Chromium, as trivalent (+3) chromium, is a trace element that is naturally present in many foods and available as a dietary supplement. Chromium also exists as hexavalent (+6) chromium, a toxic by-product of stainless steel and other manufacturing processes [ 1, 2 ]. This fact sheet focuses entirely on trivalent chromium.

The effects of chromium hydroxide calcination conditions and washing mode on the quality of chromium oxide were investigated. The results indicated that Na 2 S 2 O 3 can …

The lowest extraction values of both chromium species were characterized as 33.89% and 34.91% in presence of acetone as the nonaqueous medium. This may be …

Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. This site contains design documents, architecture overviews, testing information, and more to help you learn to build and work with the Chromium source code. Learn how to. Browse or search the sources ...

Chromium occurs mainly in the oxidation states (III) and (VI) in the environment. As well known, Cr(III) is essential for plants and animals at trace concentrations, whereas Cr(VI) is considered to be a more toxic form because of its high oxidizing potential [1, 2].For this reason, it is necessary to use a sensitive method for the …

However, it can be noticed that there is no current standard describing a method to extract and quantify Cr(III) and Cr(VI) simultaneously. A lot of studies have been conducted regarding chromium speciation in other matrices, for example foodstuffs, cosmetic products, environmental, and pharmaceutical samples [], but as far as we …

In recent decades, environmental pollution with chromium (Cr) has gained significant attention. Although chromium (Cr) can exist in a variety of different oxidation states and is a polyvalent element, only trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] are found frequently in the natural environment. In the current review, …

The average grade of the metallurgical chromite ore was 43.4 pct Cr2O3, with 52 pct of the ore having a chromium-to-iron ratio of 3:1 or over, 17.6 pct having a ratio between 2:1 and 3:1, and 30.4 pct having a ratio less than 2:1. Chemical-grade chromite ore generally ranged from 40 to 46 pct Cr2O3 with a chromium-to-iron ratio of 1.5:1 to 2:1.

The wide application of chromium will definitely increase the probability of impact of chromium-containing effluents on the surrounding environment and human health. Prior to reviewing the research progress on the liquid–liquid extraction of chromium, the common methods for treating chromium-containing wastewater and …

Chromium is the 7th most abundant element in the Earth and the 21st on the Earth's crust (0.1–0.3 mg kg −1) (Katz and Salem 1994).The most stable forms of this metal in the environment and in biological systems are the trivalent Cr(III) and hexavalent Cr(VI) (Becquer et al. 2003).Other intermediate valence states of Cr exist in nature, but they are …

Cr6+-ion extraction of chromium oxide (Cr2O3) – A clean route to chromium product manufacturing! Lidia Escudero-Castej´on, James Taylor, Sergio S´anchez-Segado, Animesh Jha *

EXTRACTION OF CHROMIUM FROM DOMESTIC CHROMITES BY ALKALI FUSION By Gary L. Hundley, 1 D. N. Nilsen, I and R. E. Siemens 2 ABSTRACT The Bureau of Mines has devised a procedure to recover chromium chemi­ cals from low-grade domestic chromites, which contain silicon and alumi­ ... been produced from domestic chromite de­ ...

6.3 To retard the chemical activity of hexavalent chromium, the samples and extracts should be stored at 4oC until analyzed. The maximum holding time prior to analysis of the samples or extracts is 24 hr. The 24 hr holding time begins after extraction. 7.0 PROCEDURE 7.1 Color development and measurement: Transfer 95 mL of the extract t o

Chromium picolinate is the form of chromium commonly found in dietary supplements. It may be effective at improving the body's response to insulin or lowering blood sugar in those with diabetes.

1. Introduction. Gallium (Ga), a soft and silvery-blue metal, was discovered in 1875 by the French chemist Paul-Émile Lecoq de Boisbaudran (Moskalyk, 2003).With an average crustal abundance of 17 ppm, Ga is considered a trace metal (Redlinger et al., 2015).This element exhibits an extraordinarily wide temperature range in the liquid state …

This document describes the method used in determining small concentrations of dissolved hexavalent chromium [Cr(VI)] in Extraction Procedure (EP) toxicity characteristic extracts and ground waters. You may need a PDF reader to view some of the files on this page. See EPA's About PDF page to learn more.. Method 7197: Chromium, Hexavalent …

The hexavalent state of chromium, which exists primarily as the tetrahedral chromate ion in aqueous solution (CrO −2 4), is able to penetrate cellular membranes using various permeases, and this penetration of membrane occurs 500–1000 times more effectively than the trivalent form [22, 23].Once inside the cell, Cr(VI) is reduced …

Chromium and its compounds give toxic and/or hazardous characteristics to all those industrial wastes, solids or liquids, that contain them. Organic solvent …

1.1 This method provides procedures for the determination of hexavalent chromium (Cr +6 ) emissio ns from hazardous waste incinerators, municipal waste incinerators, municipal waste combustor s, and sewage sludge incinerators. With the approval of the Administrator, this method may also be used to measure total chromium.

Tables 5-1 and 5-2 list the facilities in each state that manufacture or process chromium, the intended use, and the range of maximum amounts of chromium that are stored on site. The data listed in Tables 5-1 and 5 …

Removal and speciation of chromium by static step-by-step deposition and extraction technique Mohamed E. Mahmoud, Mohammed K. Obada, Taher S. Kassem …

The rate of extraction of chromium was to 97.4%. EXAMPLE 3. ... Bozel Maletra Soc Ind De Produ: Process for the preparation of monochromates and dichromates US3510256A (en) * : : Bayer Ag: Alkali treatment of chromium ores Non-Patent Citations (2) * Cited by examiner, † Cited by third party ...

Liquid–liquid extraction of chromium from industrial effluent has been investigated using tributyl phosphate as a potential extractant. Variation of parameters …

Basic oxygen furnace slags (BOS) are by-products of basic oxygen steel production. Whereas the solubility of some elements from these slags has been well investigated, information about the mineralogy and related leaching, i.e., availability of the environmentally relevant elements chromium (Cr), molybdenum (Mo), and vanadium …

Chromite deposits are mined by both underground and surface techniques. Much of the ore is rich enough to be used directly: for production of ferrochromium, a rich, lumpy ore …

Oxidative alkali roasting of chromite is the state-of-the-art process for manufacturing chromium-containing chemicals, which involves dealing with serious environmental problems arising from handling Cr 6+-containing wastes generated in this process.In this article a new method for the extraction of Cr 2 O 3 from chromite ores is …

On pouvait réduire la concentration de fer (III) dans la solution à moins de 2 mg L −1 et l'efficacité d'extraction du fer (III) pouvait atteindre jusqu'à 99.7% lorsque la valeur du pH de la solution d'alimentation, le rapport de phase, la concentration de P2O4, le taux de saponification et les étapes d'extraction étaient ...

Chromium content after sequential extraction in soil samples under oxidizing conditions in (a) unpolluted soil samples and samples spiked with different concentrations of Cr, (b) 40, (c) 80, (d ...