Sébastien Diliberto

End-of-life nickel–cadmium accumulators: characterization of electrode materials and industrial Black Mass

The aim of this paper is the characterization of spent NiCd batteries and the characterization of an industrial Black Mass obtained after crushing spent NiCd batteries and physical separation in a treatment plant. The characterization was first performed with five cylindrical NiCd batteries which were manually dismantled. Their characterization includes mass balance of the components, active powders elemental analysis and phase identification by X-ray powder diffraction. Chemical speciation of the two metals was also investigated. For cadmium, speciation was previously developed on solid synthetic samples. In a spent battery, the active powders correspond to about 43% of the battery weight. The other components are the separator and polymeric pieces (5%), the support plates (25%) and the carbon steel external case (27%). The sequential procedure shows that the nickel in the positive powders from the dismantled Ni–Cd batteries is distributed between Ni0 (39.7%), Ni(OH)2 (58.5%) and NiOOH (1.8%). Cadmium in the negative powder is about 99.9% as the Cd(OH)2 form with 0.1% of metal cadmium. In the industrial Black Mass, the distribution of cadmium is the same, whereas the distribution of nickel is Ni0 (46.9%), Ni(OH)2 (43.2%) and NiOOH (9.9%). This material contains also 1.8% cobalt and approx. 1% iron.

A zero-waste process for the management of MSWI fly ashes: production of ordinary Portland cement

ABSTRACT Municipal solid waste incineration (MSWI) fly ashes are hazardous waste since they contain organic pollutants, heavy metals and an important amount of various soluble salts. However their chemical composition is interesting for their valorization in cement production. The objective of this paper is to assess the possibility of MSWI fly ashes reuse as cement raw meal, after pre-treatment, at a laboratory scale. The environmental impact has also been studied (analyses of the metals, of dioxins and furans and leaching tests on clinker produced). Experimental results show that the replacement of MSWI fly ash could be taken up to 30% in the raw mixes, according to the chemical composition of the MSWI fly ashes. This substitution is also to be refined according to the content of hazardous elements contents. This study also shows that the pre-treatment must be well carried out in order to limit the alkaline contents which may affect the quality of the cementitious phases. GRAPHICAL ABSTRACT

Hydrodemetallation and Hydrodesulfurization Spent Catalysts Elemental Analysis: Comparison of Wavelength Dispersive X-ray Fluorescence and Atomic Emission Spectrometries

Petroleum industries continuously consume catalysts on very large scales. The recycling of spent catalysts is thus of major economic and environmental importance and its first step consists of the characterization of the valuable metal content. Wavelength dispersive X-ray fluorescence (WDXRF) analysis is compared with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the analysis of five samples of spent hydrodesulphurization (HDS) and hydrodemetallization (HDM) catalysts. The elements are considered for their economic interest (Co, Ni, Mo, and V) or for the problems that can arise when they are present in the sample in significant quantities (Al, As, P, Fe). First, the systematic comparison of the analysis of known synthetic samples was performed. The originality here is that the samples were first beaded with lithium tetraborate (Li2B4O7) for WDXRF analysis and then dissolved in hot HCl 6M for ICP-AES measurements. With this processing, we were able to clearly identify the origin of analytical problems when they arose. Second, the semi-quantitative protocol of WDXRF is compared with the quantitative procedure. Finally, the analysis of the spent catalysts is presented and the information gained by the systematic comparison of ICP-AES and WDXRF is shared. The interest of the simultaneous determination by the two techniques when such complicated heterogeneous matrices are involved is clearly demonstrated.