Densimetric Methods Research Articles

Assessment of coal washability data obtained via the RhoVol analyser

Float-and-sink analysis is widely used in the coal industry to obtain washability data, yielding important information about beneficiation potential and performance. This method is associated with health and environmental problems, and research into alternative densimetric methods is important. The RhoVol is a new technology developed by De Beers Group Technology South Africa (DebTech) for the image-based generation of densimetric data from ores. The analysis is done on a per-particle basis, within a size range of +3 mm -8 mm. In this paper we compare the established methods used for the float-and-sink analysis of coal with a new method using RhoVol. The aim of the study was to determine the validity of the information obtained from the RhoVol analyser by performing comparative densimetric analysis on three different coal samples. The results showed that the RhoVol method was more rapid, safe, and precise, but tended to consistently underestimate the density of the coal sample, probably due to varying coal porosity.

Investigations of the Density and Solubility of Ammonium Perrhenate and Potassium Perrhenate Aqueous Solutions.

Rhenium is largely used as an additive to nickel- and cobalt-based superalloys. Their resistance to temperature and corrosion makes them suitable for the production of turbines in civil and military aviation, safety valves in drilling platforms, and tools working at temperatures exceeding 1000 °C. The purity of commercial rhenium salts is highly important. Potassium, which is a particularly undesirable element, can be removed by recrystallization. Therefore, it is crucial to possess detailed knowledge concerning process parameters including the dissolved solid concentration and the resulting saturation temperature. This can be achieved using simple densimetric methods. Due to the fact that data concerning the physicochemical properties of ammonium perrhenate (APR) NH4ReO4 and potassium perrhenate (PPR) KReO4 are imprecise or unavailable in the scientific literature, the goal of this study is to present experimental data including the solubility and density of water solutions of both salts. In the experiments, a densimeter with a vibrating cell was used to precisely determine the densities. Although the investigated solutions did not fit into the earlier proposed mathematical model, some crucial conclusions could still be made based on the results.

Preliminary Studies of Slag and Ash from Incinerated Municipal Waste for Prospective Applications

The assessment of the possibility of using incinerated municipal waste, which is classified as non-hazardous, is a priority of the European zero waste strategy. The aim of this work was to identify the properties of slag and ash to develop a simple, targeted way of using post-process waste. The material was analyzed by microscopic methods in terms of composition and internal structure. Gas and water permeability tests were carried out. Slag and ash texture was obtained using densimetric methods. BCR sequential extraction was carried out to assess the impacts of the waste on the water and soil environment. It was shown that individual fractions were characterized by different compositions and pore contents. The increase in the waste layer density resulted in porosity reduction of the slag and post-process ash, which had a significant impact on permeability. The increase in density index from 0.92 to 0.98 resulted in reduction of the filtration coefficient by two orders of magnitude. The obtained results showed that the division into fractions is important for prospective applications of incinerated municipal waste. With very low permeability and negligible leachability of heavy metals, the characteristics of slag and ash predispose them to support the needs of specialized hydrotechnical construction.

Physical properties of yellow passion fruit seeds (Passiflora edulis) during the drying process

The reuse potential of passion fruit seeds to obtain functional ingredients can find many industrial applications. This requires knowledge of their physical properties for the design of conveyors and equipment. The objective of this study was to determine the physical properties of passion fruit seeds during drying and to evaluate the feasibility of using digital images to determine the dimensional properties of seeds in comparison to caliper. Passion fruit seeds with initial moisture content, in dry basis (d.b.), of 0.402 (decimal) were subjected to drying in a cylindrical tray dryer at 45 ± 2 °C to different moisture content levels and were characterized by their physical properties. Unit specific mass, mass of one thousand seeds, and seed size and shape were evaluated. The characteristic dimensions of the seeds were obtained by caliper and digital image processing. The digital image processing method was satisfactory to obtain the characteristic dimensions of passion fruit seeds. The dimensional properties did not show significant difference (P ≤ 0.05) during the drying process, indicating low contraction of the characteristic seed dimensions. The seeds presented volumetric contraction of approximately 4 %, which was represented by the Bala & Woods adapted model. The mass of one thousand seeds showed a reduction of approximately 21 % with the decrease of moisture content. The unit specific mass ranged from 1121 to 1022 kg m-3 for moisture contents of 0.402 and 0.047 (decimal, d.b.), respectively. These results indicate that the separation of passion fruit seeds as a function of moisture content should be performed by densimetric methods.

Synthesis, growth and structural investigation of Сu<sub>7</sub>SiS<sub>5</sub>I, Ag<sub>7</sub>SiS<sub>5</sub>I single crystals and solid solutions on their base

Purpose. This work is aimed at synthesis and cgrowth, X-ray investigation, study of the phase diagram and concentration behavior of lattice parameter and density of (Cu 1-х Ag x ) 7 SiS 5 I solid solutions. Methods. Alloys of Cu 7 SiS 5 I – Ag 7 SiS 5 I system were synthesized by means of direct one-temperature method from pre-synthesized Cu 7 SiS 5 I and Ag 7 SiS 5 I compounds. Growth of single crystals of (Cu 1-х Ag x ) 7 SiS 5 I solid solutions was carried out by means of crystallization from a solution-melt. Interaction in Cu 7 SiS 5 I – Ag 7 SiS 5 I system was investigated by means of differential-thermal analysis (Pt/PtRh thermocouple, heating speed 700 K/h), X-ray phase analysis (DRON 4-07, emission CuKα, angle scan step 2Θ - 0.02 deg, exposition - 0.5 s) and densimetric methods. Results. According to the results of the X-ray phase analysis, calculations of the parameters of the elementary cell of Cu 7 SiS 5 I and Ag 7 SiS 5 I compounds and based on them alloys were carried out. The diffraction patterns of Cu 7 SiS 5 I and Ag 7 SiS 5 I compounds are indexed in face-centered cubic lattice . The number and nature of the reflexes on the diffractograms of alloys containing 10-90 mol.% of Cu 7 SiS 5 I indicate that a continuous series of solid solutions is formed in the system. According to the results of differential-thermal analysis and X-ray phase analysis, a phase diagram of Cu 7 SiS 5 I - Ag 7 SiS 5 I system was constructed. It is characterized by the formation of unbounded a-solid solutions based on both compounds with a minimum on the liquidus curve (2nd type by Rozebom). The coordinates of the minimum point are 16 mol.% Cu 7 SiS 5 I, 1165 K. It is established that the compositional depenedences of the lattice parameter and density occur with a slight deviation upward from the from linear dependence. Conclusions. The synthesis and growth of single crystals of (Cu 1-х Ag x ) 7 SiS 5 I solid solutions were carried out. Alloys of Cu 7 SiS 5 I – Ag 7 SiS 5 I system were synthesized by means of direct one-temperature method from pre-synthesized Cu 7 SiS 5 I and Ag 7 SiS 5 I compounds. Growth of single crystals of (Cu 1-х Ag x ) 7 SiS 5 I solid solutions was performed by means of crystallization from a solution-melt. Interaction in Cu 7 SiS 5 I – Ag 7 SiS 5 I system was investigated by means of differential-thermal analysis, X-ray phase analysis and densimetric methods. The diffraction patterns of Cu 7 SiS 5 I and Ag 7 SiS 5 I compounds were indexed in face-centered cubic lattice . According to the results of X-ray diffraction studies, it was found that a continuous series of solid solutions is formed in Cu 7 SiS 5 I – Ag 7 SiS 5 I system. The phase diagram of Cu 7 SiS 5 I - Ag 7 SiS 5 I system is characterized by the formation of unbounded a-solid solutions based on both compounds with a minimum on the liquidus curve (2nd type by Rozebom) with the coordinates of the minimum point constituting 16 mol.% Cu 7 SiS 5 I, 1165 K. It is shown that the concentration changes of the lattice parameter and density observed with a slight deviation upward from the linear dependence.

Micellization properties of cationic gemini surfactants in aqueous solution

The main goal of this work was to investigate the self-assembly process for water solutions of two gemini surfactants, which differ in spacer chain length, at wide range of temperatures.For this reason the aqueous solutions of hexylene-1,6-bis(dimethyl-octylammonium bromide) and dodecylene-1,12-bis(dimethyloctylammonium bromide) have been examined by the calorimetric (DSC) and densimetric methods within the 293–323K and 288–323K temperature range, respectively. The analysis of cp values obtained for the examined systems allowed to propose an alternative way to estimate the region where micellization process can occur. The observed temperature dependence of the c.m.c. for surfactants investigated shows a typical shape for ionic gemini surfactants. This behavior was explained as a resultant of two competing effect: decrease in the hydrophilic properties of the surfactant molecule and decrease in the hydrophobic hydration of the alkyl chain along with the temperature increase. The enthalpy of micellization ΔHmic and other thermodynamics parameters associated with the micellization process: ΔGmic, ΔSmic and ΔCp mic were calculated on the base of the pseudo-phase separation model. As expected, more exothermic enthalpies of micellization are observed with increasing temperature for both the surfactants investigated in this work.

Calorimetric and densimetric examinations of aqueous solutions of heptylene-1,7-bis(dimethyloctylammonium bromide) and octylene-1,8-bis(dimethyloctylammonium bromide)

The critical micelle concentrations of gemini surfactants having different spacer chain lengths 8-7-8 and 8-8-8 in aqueous solutions have been determined by calorimetric and densimetric methods within a wide temperature range. The isothermal volume change upon micellisation of the title surfactants has been obtained from density measurements using pseudo-phase model. Predicted values for apparent molar volume of the surfactant at the critical micellisation concentration (c.m.c.) agree very well with infinite dilution volumes calculated from additivity method. It has been shown that the inflection point in the curves of the dependence of volume expansion coefficient on molality can be used to determine the value of c.m.c. similar as the second one of the two maxima which are observed on the concentration function of apparent molar heat capacity. The experimental determined values of c.m.c. have been compared with the values presented in the literature data for 8-s-8 gemini surfactants.

Recovery of fresh debris of different sizes in density fractions of two contrasting soils

Fresh plant residues are often identified with the light organic matter obtained by fractionation in a dense liquid, but the extent to which residues can be extracted efficiently by densimetric methods has not been widely studied. This paper presents the results of two experiments in which 14C-labelled straw was mixed with two soils of differing texture, and the mixture was subjected to densimetric fractionation. In the first experiment, soil was mixed with bulk milled straw, and in the second, with straw of different sizes (> 200 μm, 200-50 μm, 50-20 μm and < 20 μm). The recovery of straw in the light fraction was low, and decreased with decreasing straw size, reaching a minimum (less than 20 %) for straw < 20 μm. Except for straw < 20 μm, the recovery in the light fraction was lower in soil richest in silt and clay. In the absence of soil (blanks), the recovery of fine straw in the light fraction was lower than in the presence of soil, suggesting that the recovery of fine straw in the light fraction is partly due to its association with light coarse debris. Extractable and polytungstate-soluble fractions accounted for a small proportion of the 14C-activity. These results suggest that densimetric methods are not efficient for recovering fresh plant residues, except in the case of large residues in coarse-textured soils.

Flow Injection Piezoelectric Determination of Brix in Sugar Cane Juice and in the Alcoholic Fermentation Process

Abstract A flow injection piezoelectric procedure is proposed for the determination of brix (total solids dissolved) in the alcoholic fermentation process. A piezoelectric Perspex cell was constructed to fit one of the gold electrodes of a 10 MHz crystal and this sensor was adapted to a flow injection system. The analytical curve is linear over the brix range from 0.5 to 20.0% with a detection limit of 0.3%. Seventy results can be obtained per hour and the relative standard deviation was less than 1.45% for a solution containing 6% of brix (n=15). Applications of this method for the determination of brix in sugar cane juice and in an alcoholic fermentation bench show satisfactory results in comparison with refractometric and densimetric methods, respectively.

Newborn response to auditory stimulation as a function of postural tilt and state

The main goal of this work was to investigate the self-assembly process for water solutions of two gemini surfactants, which differ in spacer chain length, at wide range of temperatures.For this reason the aqueous solutions of hexylene-1,6-bis(dimethyl-octylammonium bromide) and dodecylene-1,12-bis(dimethyloctylammonium bromide) have been examined by the calorimetric (DSC) and densimetric methods within the 293–323 K and 288–323 K temperature range, respectively. The analysis of cp values obtained for the examined systems allowed to propose an alternative way to estimate the region where micellization process can occur. The observed temperature dependence of the c.m.c. for surfactants investigated shows a typical shape for ionic gemini surfactants. This behavior was explained as a resultant of two competing effect: decrease in the hydrophilic properties of the surfactant molecule and decrease in the hydrophobic hydration of the alkyl chain along with the temperature increase. The enthalpy of micellization ΔHmic and other thermodynamics parameters associated with the micellization process: ΔGmic, ΔSmic and ΔCp mic were calculated on the base of the pseudo-phase separation model. As expected, more exothermic enthalpies of micellization are observed with increasing temperature for both the surfactants investigated in this work.

Size and shape of nonionic micelles determined by x-ray scattering techniques

Small angle X-ray scattering studies on aqueous solutions of the nonionic detergents Triton X-100, Lubrol WX, and two other n-alkyl polyoxyethylene ethers, in the concentration range of 5–15 mg/ml were performed and their size, degree of hydration and radii of gyration were determined. By densimetric methods the partial specific volumes were determined and compared with the values obtained from X-ray scattering techniques at different contrast. The radii of gyration for the nonionic detergents in aqueous solutions at T = 293°K were found to be in the range of R g = 29.5–34.5 A, their volumes in the range of 3.35–4.15 × 10 5 A 3 and their degree of hydration about 1.15 g H 2O/g micelle. However, the inverted micelle of Triton X-100 in hexane, containing 0.03–0.05% (w/w) water, has a radius of gyration of R g = 10.2 A. The behavior of the hydrophobic part of the Triton X-100 micelles In aqueous and nonaqueous solutions was studied with tag-labelled iodine, introduced into the phenyl ring, by means of X-ray scattering at various contrast. Assuming a two-level step function in electron density within the Triton X-100 micelles, the high electron density regions extend to R = 25.7 A ( T = 293°K), determined from the iodine labelled phenyl ring. From the correlation function, calculated directly from the scattering data, the hydrocarbon core of the tag-labelled Triton X-100 yields a maximum dimension of 48.0 A. The value of the average curvature of the tag-labelled hydrophobic core of Triton X-100 was determined to 1/23.6 A, smaller than the average radius calculated from the radius of gyration for the hydrophobic part. This shows that the core surface is convoluted, e.g., some oxyethylene chains must be embedded in the hydrophobic core, indicating that there is no direct sharp boundary between the hydrophobic interior and the oxyethylene units. Whereas the largest dimensions of the Triton X-100 micelles as well as of Lubrol WX are 107–110 A at T = 293°K, determined from the correlation function, the extension in solution of the inverted micelle of Triton X-100 was found to be 26.5 A. Density homogeneities, namely variations of the average density of the Triton X-100 particles, can introduce anomalies in I (O, p o) and R g 2 ( p o) close to buoyancy and the critical point. The data suggest that between 20–50°C the scattering data in 0.01 M TRIS-HCl are influenced by internal density fluctuations, e.g., entrapping of water, rather than micelle size.

ADVANCES IN MAGNETIC SEPARATION TECHNIQUES OF PARTICULATE SYSTEMS

Abstract Magnetic techniques are available today for the separation, characterization, and preparation of samples of particulate systems. In particular the methods derived from the High Intensity-High Gradient, and from the Magnetohydrostatic separation techniques provide increased degree of resolution and reliability. In this context the basic features of the densimetric and susceptibilily fractionation methods arc described. The basic theories, useful field geometries, and procedures for application are reviewed. The novel magnetic differential susceptibility and the three-dimensional axial separation systems are looked at, and their potential uses for studies of particulates are discussed.

Reinvestigation of Densimetric Methods of Ring Analysis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReinvestigation of Densimetric Methods of Ring AnalysisTEH FU YEN, J. GORDON ERDMAN, and WILLIAM E. HANSONCite this: J. Chem. Eng. Data 1961, 6, 3, 443–448Publication Date (Print):July 1, 1961Publication History Published online1 May 2002Published inissue 1 July 1961https://doi.org/10.1021/je00103a033RIGHTS & PERMISSIONSArticle Views62Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (590 KB) Get e-Alerts Get e-Alerts

Report on Drying, Densimetric and Refractometric Methods

Report on Drying, Densimetric and Refractometric Methods