Caracterización y valorización de residuos inorgánicos procedentes de industrias químicas de Huelva

Supervised by:
  1. Juan Pedro Bolívar Raya Director
  2. Manuel Jesús Gázquez González Director

Defence university: Universidad de Huelva

Fecha de defensa: 26 February 2018

  1. Maximina Romero Pérez Chair
  2. Rafael Pérez López Secretary
  3. Joao Labrincha Committee member

Type: Thesis


Waste is currently one of the most serious environmental problems arising from the economic and social development of human beings, mainly because of the amount of waste continues to increase year after year. The emergence of materials more resistant to natural degradation processes, which remain longer in the environment, and the increase in their dangerous characteristics, are factors that aggravate the current situation of waste. The high generation of waste that accompanies economic growth without limits, causes not only the lack of space and inadequate treatments to eliminate them, but also a depletion of the resources used in their manufacture. Therefore, it is necessary to find solutions to these environmental problems that allow the sustainable development of our society. In this sense, the industrial complex located in Huelva is today one of the main industrial center of Spain. The presence of industrial focus in this city has contributed for more than half a century very positive effects in the creation of employment and wealth generation, But also, it has generate environmental problems. Such problems are identified as waste generation; wastewater release, and gas emissions between others, which suppose source of release pollutant into the water, soil and atmosphere that couid adversely affect to the environment and health of human. The main objective of this doctoral thesis has been to characterise physically and chemically different industrial wastes produced In several factories the industrial complex from Huelva, and also find commercial applications in which they can be used without implying any risk for environment or people. The studied wastes has been: red gypsum and ilmenite mud generated in the TÍO2 production industry; reprocessed slag cleaning furnace flue dust from copper smelting; and phosphogypsum from phosphoric acid production industry. Some of them are considered as NORM (Naturally Occurring Radioactive Material). For that purpose, a number of instrumental techniques were deployed to characterise the wastes and the new materials designed, such as, laser diffraction particle sizing analysis, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Inductively Coupled. Plasma Optical EmissiQmSpectroscopy4IC[^OES)r.-Inductively-Xoupled.-Blasma;-Mass. Spectrometry (ICP-MS), Scanning Electron Microscopy (SEM), Thermogravimetry (TGA/DTA), aipha-particle spectrometry with PIPS detectors and gamma spectrometry with Ge detectors. In addition several tests were applied in order to evaluate the environmental and radiological implications of the studied wastes, as well as evaluate the technological properties of new obtained material. The researches carried out involve the use of red gypsum (RG) and tionite as potential building materials for fire wail insulation or as fire-resistant panels. The study demonstrated that plates manufactured with RG (main components: CaS04'2H20) and iron and titanium oxides) and tionite (main components: FeTi03, TiCh, ZrSi04, SÍO2 and FesTbOio) perform better than some materials used in construction such as Piadur® against fire. The tested materials also present acceptable mechanical properties that showed no noticeable distortion or breakage during the test. In addition, it has been proven that the plates manufactured are agree with EU radioactivity requirements, since the use of these wastes as building materials not exceeded the radioactive thresholds. Furthermore, RG was proposed as a source for CO2 sequestration. The results show that RG could be used as capture agent for carbon dioxide sequestration. It has been demonstrate that a high carbonation efficiency is reached using NaOH as Ca extracting agent, as weli as a reduction of the resulted solid. However, the natural radionuclides are concentrated In calcite (CaC03), the main product of the carbonation process, which implies its consideration as a NORM material, which requires radiological studies in their commercial applications. On the other hand, flue dust from copper smelting was subjected to an exhaustive characterization as an indispensable preliminary step to choose the best available technology to recover their major metals, principally Zn and Pb, which are in form of zincite (ZnO), carbonate (PbC03) and sulphate (PbS04). It has been demonstrated that the wastes are an important secondary resource of Zn and Pb and their reprocessing has both remarkable economic and environmental benefits in contrast with their disposal. Pyrometailurgical and hydrometailurgical process appears to be attractive options for the management of these hazardous wastes. Finally, the environmental impact due to natural radionuclides contained in the phosphogypsum (PG) stored in Huelva, was evaluated using the BCR sequential extraction method, previously validated for radionuclides. This aspect is essential because the release of the pollutant into the environment depend strongly on their specific chemical forms or ways of binding. It has been demonstrated that the BCR sequential extraction procedure is a useful tool for assessing the speciation of different radionuclides due to reproduces environmental conditions. In this sense, the results shown that U-isotopes contained in PG show highest mobility, being its total mobile fraction around 70%, while 210Po and ^Ra present a total mobility of about 50% and 30%, respectively. And the Th- isotopes have very low mobility (mobile fraction < 5%), being fixed to the crystalline forms of the PG. This behaviour was also found in the water samples taken from the stacks.