Determination of chromium (VI) in the dust of gas treatment plants in steelmaking plants.

Abstract

The requirements for the content of hexavalent chromium in cements and raw materials for its manufacture are described. The problem with the utilization of dust from gas treatment plants of metallurgical plants at metallurgical enterprises is given. The influence of the chemical composition of the dust of gas cleaning plants of metallurgical plants on the determination of hexavalent chromium is established. A method for measuring the hexavalent chromium in the dust of gas cleaning plants of metallurgical plants by the photometric method is described. A method has been developed for extracting hexavalent chromium from dust at the cleaning units of metallurgical plants for subsequent photometric determination. An extraction method has been established to prevent underestimation of the hexavalent chromium content. The determination of hexavalent chromium was based on the formation of a blue-violet complex with diphenylcarbazide. Calibration was carried out on aque solutions with a known concentration of hexavalent chromium. For the preparation of calibration solutions, potassium dichromate of chemical purity was used. The concentration of hexavalent chromium in each calibration solution was carried out by a calculation method, overlapping the entire measurement range. The measurement of optical density was carried out on a photoelectric colorimeter type KFK-3, at a wavelength of 540 nm. Analysis of the obtained calibration dependence showed a good correlation. The calibration factor was calculated using the least square method. Extraction of hexavalent chromium from the sample to be analyzed was performed with water. The reducing effect of iron was eliminated with a solution of phosphoric acid. The developed technique is used when conducting certification control of dust from gas cleaning units of metallurgical plants, as well as during research.A validation procedure was carried out. Obtained acceptable limits of repeatability and reproducibility of the method.