scholarly journals Conditions of accumulation and fractionation of zirconium and hafnium in alkaline-carbonatite systems

2019 ◽  
Vol 64 (12) ◽  
pp. 1215-1221
Author(s):  
L. N. Kogarko
Keyword(s):  
Distribution Coefficient ◽  
Primary Magma ◽  
Crystallization Field ◽  
Main Process ◽  
Magmatic System ◽  
Accessory Minerals ◽  
Continuous Crystallization ◽  
Crystallization Differentiation

The patterns of the distribution and fractionation of strategic metals (Zr, Hf) in the Kugda intrusion (Polar Siberia) have been studied. The contents of these elements significantly exceed their concentrations in other rocks (Zr 246 ppm, Hf 7.4 ppm). A significant increase in Zr and Hf from early rocks (olivinite and melilite rocks) to later differentiation products, syenites with up to 570 ppm of Zr and 16 ppm of Hf, has been revealed. During the evolution of the Kuga magmatic system, notable fractionation of Zr and Hf occurred. The Zr/Hf ratios in the dike rock, similar in composition to the primary Kugda Massif magma, and the early intrusions are fairly close to that of chondrite (Zr/Hf = 37 [1]), while in the latest phases this ratio increases by almost 5-fold. Our study showed that the distribution coefficient of Hf (Kd = 0.58) in alkaline pyroxenes is noticeably higher than that of Zr (Kd = 0.40). Consequently, fractionation of this mineral leads to an increase in the Zr/Hf ratio in the residual liquids. Another mineral concentrating up to 400 ppm of Zr and up to 1520 ppm of Hf is perovskite, which has a very wide crystallization field in the rocks of the Kugda Massif, especially in the earliest olivinite. The data obtained showed that the Zr/Hf ratio in the perovskite of olivinite varies between 2327, that is, noticeably below both the chondritic and the primary magma values. Early crystallization of perovskite is the main reason for increasing the Zr/Hf ratio in melilitolites (up to 54). Thus, the main process of forming the Kugda Massif was continuous crystallization differentiation, accompanied by a noticeable fractionation of rock-forming and accessory minerals (pyroxene and perovskite).

Igneous evolutions across the Ivrea crustal section: the Permian Sesia Magmatic System and the Triassic Finero intrusion and mantle

2014 ◽  
Vol 6 (2.2) ◽  
pp. 1-98 ◽  
Author(s):  
Maurizio Mazzucchelli ◽  
James E. Quick ◽  
Silvano Sinigoi ◽  
Alberto Zanetti ◽  
Tommaso Giovanardi
Keyword(s):  
Magmatic System

CHEMICAL PULPING. Oxidative degradation of AOX in softwood-based kraft mill effluents from E C F bleachin g

2012 ◽  
Vol 27 (4) ◽  
pp. 707-713 ◽  
Author(s):  
Jukka Pekka lsoaho ◽  
Suvi Tarkkanen ◽  
Raimo Alen ◽  
Juha Fiskari
Keyword(s):  
Reaction Time ◽  
Oxidative Degradation ◽  
Cost Effective ◽  
Process Conditions ◽  
Main Process ◽  
Chemical Pulping ◽  
Kraft Mill ◽  
Organic Halogens ◽  
Aox Removal ◽  
Adsorbable Organic Halogens

Abstract Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E 1D 1 E2D2) were treated by the oxidative Fenton method (H20rFeS04) to decompose organic pollutants contammg adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H202 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adj usted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E 1 was 3 :2). The results indicated that an AOX removal of about 70% for this mixture ( corresponding to about 50% for the mill) was achieved when the eftluent samples were treated for 60 min at 70°C with H202 and Fe2+ at a concentration of 1 600 mg/1 and 28 mg/1, respectively.

IMAGE THRESHOLDING BASED ON HIERARCHICAL CLUSTERING ANALYSIS AND PERCENTILE METHOD FOR TUNA IMAGE SEGMENTATION

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Alifia Puspaningrum ◽  
Nahya Nur ◽  
Ozzy Secio Riza ◽  
Agus Zainal Arifin
Keyword(s):  
Image Segmentation ◽  
Hierarchical Clustering ◽  
Gabor Filter ◽  
Hierarchical Cluster ◽  
Experimental Result ◽  
Main Process ◽  
Percentile Method ◽  
Cluster Analysis Method ◽  
2D Gabor Filter

Automatic classification of tuna image needs a good segmentation as a main process. Tuna image is taken with textural background and the tuna’s shadow behind the object. This paper proposed a new weighted thresholding method for tuna image segmentation which adapts hierarchical clustering analysisand percentile method. The proposed method considering all part of the image and the several part of the image. It will be used to estimate the object which the proportion has been known. To detect the edge of tuna images, 2D Gabor filter has been implemented to the image. The result image then threshold which the value has been calculated by using HCA and percentile method. The mathematical morphologies are applied into threshold image. In the experimental result, the proposed method can improve the accuracy value up to 20.04%, sensitivity value up to 29.94%, and specificity value up to 17,23% compared to HCA. The result shows that the proposed method cansegment tuna images well and more accurate than hierarchical cluster analysis method.

Mathematical modelling of salt purification by recrystallization. Countercurrent arrangement

1986 ◽  
Vol 51 (11) ◽  
pp. 2481-2488
Author(s):  
Benitto Mayrhofer ◽  
Jana Mayrhoferová ◽  
Lubomír Neužil ◽  
Jaroslav Nývlt
Keyword(s):  
Steady State ◽  
Simple Model ◽  
Mathematical Modelling ◽  
Distribution Coefficient ◽  
Mother Liquor ◽  
Equilibrium Temperature ◽  
Operating Conditions ◽  
Limiting Case

The paper presents a simple model of recrystallization with countercurrent flows of the solution and the crystals being purified. The model assumes steady-state operating conditions, an equilibrium between the outlet streams of each stage, and the same equilibrium temperature and distribution coefficient for all stages. With these assumptions, the model provides the basis for analyzing the variation in the degree of purity as a function of the number of recrystallization stages. The analysis is facilitated by the use of a diagram constructed for the limiting case of perfect removal of the mother liquor from the crystals between the stages.

Computational Parameters in Correlation Analysis: Gas-Water Distribution Coefficient

1999 ◽  
Vol 64 (11) ◽  
pp. 1727-1747 ◽  
Author(s):  
George R. Famini ◽  
Dalia Benyamin ◽  
Christina Kim ◽  
Rattiporn Veerawat ◽  
Leland Y. Wilson
Keyword(s):  
Correlation Analysis ◽  
Distribution Coefficient ◽  
Water Distribution ◽  
Solvation Energy ◽  
Linear Solvation Energy Relationships ◽  
Linear Solvation Energy Relationship ◽  
Energy Relationships ◽  
Linear Solvation Energy ◽  
Water Equilibrium ◽  
Linear Solvation

Theoretical linear solvation energy relationships (TLSER) combine computational molecular parameters with the linear solvation energy relationship (LSER) of Kamlet and Taft to characterize and predict properties of compounds. This paper examines the correlation of the gas-water equilibrium constant for 423 compounds with the TLSER parameters. Also, it describes new parameters designed to improve the TLSER information content.

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