Effect of Oxygen Content and Temperature On Stabilization of Arsenic in Copper Smelting System

Arsenic-bearing wastes from copper smelting system are usually disposed by trapping them in slag tailing. However, arsenic in slag tailing is not that stable, which can infiltrate into the groundwater, threatening the environment and human health. The solidification/stabilization (S/S) of arsenic is the only way to deal with arsenic contamination. The flash smelting method shows relatively high S/S ability of arsenic, but the process and mechanism remain unclear. In this paper, we aim at revealing the effect of atmosphere on the S/S process of arsenic owing to the different content of oxygen in reaction shaft and sedimentation tank in copper smelting system. Calcium arsenate, SiO2, Fe2O3 and iron powders were sintered at different temperature in air and argon to simulate the S/S reaction. The results show that the sintering product is Fe-Si oxide in air and fayalite in argon, and the fayalite possesses better capacity to solidify arsenic than that of Fe-Si oxide. The toxicity characteristic leaching procedure (TCLP) results reveal that the leached concentration of arsenic from fayalite fabricated at 1200 ℃ is only 2.916 mg L-1, which satisfies the identification standard for hazardous substances in China. Furthermore, the theoretical calculation reveals that AsO4 and SiO4 tetrahedrons can be connected by O atoms when sintered in argon, and the Si-O-As covalent bond can evidently inhibit the release of As atom from fayalite. This work can not only clarify the S/S mechanism of arsenic in flash smelting process, but also provide theoretical guidances to dispose arsenic-bearing waste harmlessly.

The synthesis of calcium arsenate@iron arsenate coating materials and their application for arsenic-containing wastewater treatment

Calcium arsenic salts converted to coating materials by ferric salts. The coating materials can be used for arsenic immobilization.

Correction: The synthesis of calcium arsenate@iron arsenate coating materials and their application for arsenic-containing wastewater treatment

Correction for ‘The synthesis of calcium arsenate@iron arsenate coating materials and their application for arsenic-containing wastewater treatment’ by Yang Wang et al., RSC Adv., 2020, 10, 719–723.

Selective Separation of Arsenic from Lead Smelter Flue Dust by Alkaline Pressure Oxidative Leaching

This study investigated the feasibility of using an alkaline pressure oxidative leaching process to treat lead smelter flue dust containing extremely high levels of arsenic with the aim of achieving the selective separation of arsenic. The effects of different parameters including NaOH concentration, oxygen partial pressure, liquid-to-solid ratio, temperature, and time for the extraction of arsenic were investigated based on thermodynamic calculation. The results indicated that the leaching efficiency of arsenic reached 95.6% under the optimized leaching conditions: 80 g/L of NaOH concentration, 1.0 MPa of oxygen partial pressure, 8 mL/g of liquid-to-solid ratio, 120 °C of temperature, 2.0 h of time. Meanwhile, the leaching efficiencies of antimony, cadmium, indium and lead were less than 4.0%, basically achieving the selective separation of arsenic from lead smelter flue dust. More than 99.0% of arsenic was converted into calcium arsenate product and thus separated from the leach solution by a causticization process with CaO after other metal impurities were removed from the solution with the addition of Na2S. The optimized causticization conditions were established as: 4.0 of the mole ratio of calcium to arsenic, temperature of 80 °C, reaction time of 2.0 h. The resulting product of calcium arsenate may be used for producing metallic arsenic.

O6B.1 Use of arsenical pesticides and risk of lung cancer among french farmers

ContextExposure to inorganic arsenicals, including occupational use of pesticides, is carcinogenic to the lung (IARC group 1). However epidemiological data are scarce for agricultural exposures. This work assesses lung cancer (LC) risk, including duration-effect relationships, associated to arsenicals use in farming, by gender and histology.MethodsWe linked data from two French projects: (1) the Agriculture and Cancer (AGRICAN) cohort, a large prospective cohort of farmers and people affiliated to the French agricultural insurance scheme and (2) the Pesticide Matrix (PESTIMAT), a crop-exposure matrix. Incident lung cancer cases were collected and their histological subtype ascertained from cancer registries, from enrolment (2005–2007) to December 31 st 2013. The enrolment questionnaire included items on smoking history, and the involvement in 18 different breedings/crops and specific tasks, including pesticide application, with years of beginning and end. We performed Cox models, with age as timescale, adjusted on gender, smoking, and two activities found to be protective in previous analyses – cattle breeding and corn growing. The reference group included farmers having never applied any pesticide on any crop. We assessed risks for each inorganic compound (lead, sodium, aluminum, copper and calcium arsenate) and for overall exposure.ResultsNearly 10% (n=14 359 people) of the population was potentially exposed to arsenicals, in vineyard growing before 2001, or in fruit-tree or potato growing before 1973. We observed 98 incident LC among exposed people. Only women exhibited a higher risk of LC (HR 3.14 95% CI(1.42–6.96) for exposure to any compound, n=7 exposed cases, all adenocarcinomas), but with no duration-effect relationship. Risks were significantly elevated for lead, copper and sodium arsenate.ConclusionWe found an increased risk of LC, especially adenocarcinomas, among women. At this stage, exposure assessment was broad: the use of an exposure index, based on probability, frequency and intensity of use, will help refine the analyses.