Person: Tijero Miquel, Julio Félix
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First Name
Julio Félix
Last Name
Tijero Miquel
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Area
Ingeniería Química
Identifiers
4 results
Search Results
Now showing 1 - 4 of 4
Item Improving deposition tester to study adherent deposits in papermaking(Chemical Engineering Research and Design, 2012) Monte Lara, María Concepción; Sánchez, Mónica; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixConventional methods used for the quantification of adherent material contained in a pulp suspension propose either filtration of the sample, which may lead to loss of sticky material in the filtrate, or dilution of the pulp, which may cause destabilization of the dissolved and colloidal material; thus, leading to unreliable results. In 1998, the Cellulose and Paper Group of University Complutense of Madrid developed a deposition tester which aimed to quantify the adherence of material (microstickies and secondary stickies from dissolved and colloidal material) that was present in white waters generated during papermaking processes. In this paper, an improved deposition tester capable of directly studying the deposition tendency of total stickies in pulps without dilution is described and validated. The design of this device prevents the rotor system from being clogged and blocked by pulps, hence, being able to quantify deposits without having to apply any filtration and/or dilution stages. In addition, the study provides determination of the equipment optimum operating conditions as well as comparison between the improved deposition tester and the one previously developed. Results show that this deposition tester can determine the adherent material contained in pulps with a consistency up to 1%. The comparison of results obtained after applying both deposition quantification methods shows that the quantities of deposits that were measured with the improved tester are slightly lower than those obtained with the application of the conventional method; however, they are in the same order of magnitude. Therefore, it is possible for the improved tester to determine total stickies in all cases, including cases that it is not convenient to apply a filtration and/or a dilution stage.Item Pitch adsorption on natural and modified talcs(Journal of Pulp and Paper Science, 2009) Tijero Cruz, Antonio; Monte Lara, María Concepción; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixTalc is used traditionally for pitch control in papermaking. The effectiveness of talcs as control agent of dissolved and colloidal pitch depends on its structural and surface characteristics of minerals. Talcs are modified by thermal and surface treatments to obtain different properties e.g specific surface, surface energy, surface charge and ratio lypophilic/hydrophilic surface. Five commercial talcs have been tested to determine its capacity to adsorb the lypophilic contaminants by experiments of adsorption isotherms. The talcs correspond to two groups of different mineralogical compositions: one with high concentration of talc and some dolomite; and the other, with medium concentrations of talc and chlorite. Colloidal dispersions of extractives were obtained by extraction of Eucalyptus globulus wood at pilot plant scale with acetone, evaporation of the solvent and reextraction with hexane to increase the selectivity of lypophillic compound extraction. The isotherms of adsorption of the pitch dispersions were carried out at 50ºC on the different talcs. The adsorption took place by a mechanism of colloidal adsorption and the results obtained were adjusted to the Langmuir equation. Results show that talc addition to bleaching waters or process waters can produce high reductions of colloidal pitch concentrations, at comparatively low doses.Item Development of a methodology to predict sticky deposits due to dissolved and colloidal material destabilization in papermaking - Application to different systems(Chemical Engineering Journal, 2004) Monte Lara, María Concepción; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixDue to trends in papermaking like closed water systems or higher use of recovered paper as raw material, a large number of contaminants are accumulated in the system as dissolved and colloidal material (DCM). When the DCM is destabilized by a sudden change in the system conditions, it produces sticky deposits called secondary stickies that affect the papermaking processes and the quality of the final product. The laboratory methods existing to predict DCM destabilisation have limitations as low reproducibility or they do not distinguish between sticky and non-sticky materials and/or high volumes are necessary to perform the test, etc. In order to solve these problems, a methodology to predict the depositability potential of DCM has been developed by the Complutense University of Madrid. The methodology is based, first, on the destabilisation of the DCM by polymer addition, second, on its deposition on the collector surfaces and, third, on the quantification of the formed deposits by image analysis. Results show that the methodology has a good reproducibility with an error below 10%. Validation was carried out by application of the method to different cases. Results demonstrate that the developed methodology is a useful tool for researchers and papermakers to predict deposit problems due to the destabilisation of DCM in papermaking.Item Stickies removal in a deinking line of a newsprint mill: efficiency of the different process stages(Cellulose Chemistry and Technology, 2006) Miranda Carreño, Rubén; Blanco Suárez, María Ángeles; Negro Álvarez, Carlos Manuel; Tijero Miquel, Julio FélixThe study evaluates stickies removal efficiency of the different process stages in a deinking line of a newsprint paper mill, using 100% recovered paper as raw material. Two different situations have been considered, namely, a normal one, with a low level of stickies at the beginning of the line, and a critical situation with a high level of stickies. Removal efficiencies have been compared with data available in the literature. Although results show a high efficiency of the process for contaminants removal in both cases (80-90%), residual stickies levels at the end of the line are very different (a double initial stickies content causes four times higher stickies content at the end of the line). The first loop is the most critical step, removing 72% of the inlet stickies to the line. The most efficient units are preflotation and the second thickening stage (disc filter 2).