Recycling of Cr/Ni/Cu plating wastes as black ceramic pigments

Abstract

The non-ferrous metal industry, such as Cr/Ni/Cu plating, produces acid sludge which is usually neutralized with lime slurry in batch processes, and the resulting waste is dewatered by vacuum filtration or filter-pressing. Dewatered sludge contains calcium sulphate (CaSO 4) coming from the neutralization process, as well as transition metals (Cr, Ni and Cu), oil, grease and suspended solids. In this communication, two residual sludges from Cr/Ni/Cu plating have been dried (110 ºC) and fired (1100 ºC), and both dried (gray coloured) and fired powders (black coloured) have been characterized by DTA-TG, XRD and SEM-EDX techniques. XRD shows only quartz crystallization in dried samples, while NiCr 2 O 4 chromite spinel and NiO periclase crystallize in fired powders, along with CaSO 4 anhydrite and CaSiO 3 wollastonite. The powders have been introduced as ceramic pigments into three different conventional glazes: a) a lead bisilicate (PbO.2SiO 2) double fire frit (1000ºC), b) a double fire frit with low lead content (1000ºC), and c) a double fire frit without lead (1050ºC). Glazed samples were characterized by UV-Vis-NIR (diffuse reflectance) and CIEL*a*b* (color parameters). Dried powders induce glaze defects (pin-holing and crawling), but fired powders did not show these faults exhibiting more intense (higher L*) and yellowish (higher b*) black colors than the standard spinel.

Waste-Based Pigments for Application in Ceramic Glazes and Stoneware Bodies

“…The use of industrial wastes, some of them hazardous, to synthetize inorganic pigments for ceramic applications has been a topic explored in the last years [3,4,5,6,7,8,9,10,11,12,13]. Some examples of industrial wastes used as secondary raw materials for the pigment’s synthesis include: titanium slag [3], ashes from anaerobic treatment of municipal sewage [4], electroplating sludge [5,6,7,8,9], leather sludge [10,11], red mud [7,12], and rice husk biomass [13].…”

“…Some examples of industrial wastes used as secondary raw materials for the pigment’s synthesis include: titanium slag [3], ashes from anaerobic treatment of municipal sewage [4], electroplating sludge [5,6,7,8,9], leather sludge [10,11], red mud [7,12], and rice husk biomass [13]. …”

Submicronic spherical inclusion black pigment by double‐shell reaction sintering

“…As far as we know, however, it is difficult to meet “green” target due to heavy metal concerns and the recognition that Co resources are limited . Many studies about nontoxic candidate and the re‐utilization of industrial waste have emerged, aiming to solve these problems . CB (carbon black) @ZrSiO 4 inclusion pigments was positioned as a promising alternative to spinel black ceramic pigments, which has been performing well on ceramic glaze for a long time at the research level.…”

“…[4][5][6] Many studies about nontoxic candidate and the re-utilization of industrial waste have emerged, aiming to solve these problems. 3,4,[7][8][9][10][11][12][13][14] CB (carbon black) @ZrSiO 4 inclusion pigments was positioned as a promising alternative to spinel black ceramic pigments, which has been performing well on ceramic glaze for a long time at the research level.…”

Síntese de pigmentos de níquel utilizando areia descartada de fundição como fonte de sílica

“…No entanto, seu custo e limitação de espaço tornam necessária a busca de alternativas para a utilização destes resíduos [5,6]. Uma alternativa seria utilizar estes resíduos como matéria-prima em outras atividades [4,7]. Entende-se que o resíduo de uma empresa pode ser um material com potencial econômico para outra [8], minimizando os problemas ambientais [9].…”