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Abstract

The entropy production per unit time is calculated for the regular lamellae -, and for the regular rods formation, respectively. The entropy production is a function of some parameters which define the eutectic phase diagram, coefficient of the diffusion in the liquid, and some capillary parameters connected with the mechanical equilibrium located at the triple point of the solid/liquid interface. Minimization of the entropy production allowed to formulate mathematically the so-called Growth Law for both envisaged eutectic morphologies.

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Authors and Affiliations

W. Wołczyński
ORCID: ORCID
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Abstract

The (Zn) – single crystal strengthened by the E = (Zn) + Zn16Ti eutectic precipitate is subjected to directional growth by the Bridgman’s system and current analysis. Experimentally, the strengthening layers (stripes) are generated periodically in the (Zn) – single crystal as a result of the cyclical course of precipitation which accompanies the directional solidification. These layers evince diversified eutectic morphologies like irregular rods, regular lamellae, and regular rods. The L – shape rods of the Zn16Ti – intermetallic compound appear within the first range of the growth rates when the irregular eutectic structure is formed. Next, the branched rods transform into regular rods and subsequently the regular rods into regular lamellae transitions can be recorded. The regular lamellae exist only within a certain range of growth rates. Finally, the regular rods re-appear at some elevated growth rates.

A new solution to the diffusion equation is provided to describe the micro-field of the solute concentration in the liquid adjacent to the front of the growing eutectic structure. The solution is based on the mass balance in the considered system. Moreover, the existence of the protrusion of the leading eutectic phase over the wetting one is required by the mass balance. The appearance of the d – protrusion in the growing eutectic is well confirmed by the experimental observations of the frozen solid/liquid interface. The mentioned solution satisfies the concept of the eutectic coupled growth according to which undercooling of the leading phase is less than undercooling of the wetting eutectic phase. Also, the Ti – solute micro-segregation / redistribution is analyzed within the matrix of the single crystal. The micro-segregation is described as a result of the solution to the adequate, newly developed differential equation. The definition for the solute redistribution is given by the subsequently / separately formulated relationship. This definition takes into account both extent -, and intensity of the solute redistribution.

Finally, the entropy production is calculated for the regular lamellae -, and for the regular rods formation, respectively. The entropy production is a function of some parameters which define the eutectic phase diagram, coefficient of the diffusion in the liquid, and some capillary parameters connected with the mechanical equilibrium located at the triple point of the solid/liquid interface. Branches formation is related to the marginal stability. A new criterion is formulated and subjected to successful verification. It is: in the structural – thermodynamic competition the winner is this kind of the pattern for which minimum entropy production has a lower value.

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Authors and Affiliations

W. Wołczyński
ORCID: ORCID
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Abstract

Experimental observations of the steel morphology as well as measurements of the solutes concentration in the macro-scale were made on the basis of the vertical cut at the mid-depth of the 15-tons steel forging ingot serially produced in one of the steel plant in Poland. Experimental observations of the morphology accompanied by the measurements of the Peclet Number were also made on the cross-section of the continuously cast brass ingots serially produced in the copper / brass industry in Poland. The performed measurements allowed to work out some maps of the alloying elements segregation for the longitudinal section of the steel static ingot and a Growth Law for the columnar grains formation in the brass ingots. The marginal stability criterion has been applied to the last mentioned development / description. Some suggestions for the micro-segregation measurement mode in the columnar structure are derived.

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Authors and Affiliations

W. Wołczyński
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Abstract

Coagulation and solidification of the copper droplets suspend in the liquid slag are usually accompanied by the appearance of the Cu-Cu2O eutectic. Locally, this eutectic is created in the stationary state. Therefore, frequently it has a directional morphology. Since the E = (Zn) + Zn16Ti – eutectic is similar in the asymmetry of the phase diagram to the Cu-Cu2O – eutectic, the (Zn) single crystal strengthened by the E = (Zn) + Zn16Ti precipitate is subjected to directional growth by the Bridgman’s system and current analysis. Experimentally, the strengthening layers (stripes) are generated periodically in the (Zn) – single crystal as a result of the cyclical course of precipitation which accompanies the directional solidification. These layers evince diversified eutectic morphologies like irregular rods, regular lamellae, and regular rods. The L – shape rods of the Zn16Ti – intermetallic compound appear within the first range of the growth rates when the irregular eutectic structure is formed. Next, the branched rods transform into regular rods and subsequently the regular rods into regular lamellae transitions can be recorded. The regular lamellae exist only within a certain range of growth rates. Finally, the regular rods re-appear at some elevated growth rates. The entropy production per unit time and unit volume is calculated for the regular eutectic growth. It will allow to formulate the entropy production per unit time for both eutectic structure: rod-like and lamellar one.

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Authors and Affiliations

W. Wołczyński
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Abstract

A brief description of the innovative mathematical method for the prediction of CET – localization in solidifying copper and copper alloys’ ingots is presented. The method is to be preceded by the numerical simulation of both temperature field and thermal gradient filed. All typical structural zones were revealed within the copper and copper alloys’ massive ingots or rods manufactured by continuous casting. The role of thermal gradient direction for the single crystal core formation has been enlightened. The definition for the index describing proportion between volume fraction of the columnar structure and volume fraction of the equiaxed structure has been formulated by means of the interpretation of some features of the liquidus isotherm velocity course. An attempt has been undertaken to apply the developed mathematical method for the structural zones prediction in the rods solidifying under industrial conditions. An industrial application has been shown, that is, it was explained why the innovative rods should be assigned to the overhead conductors in the electric tractions.
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Authors and Affiliations

P. Kwapisiński
1
ORCID: ORCID
W. Wołczyński
2
ORCID: ORCID

  1. KGHM Polska Miedź S.A., M. Skłodowskiej-Curie 48, 59-301 Lubin, Poland
  2. Institute of Metallurgy and Materials Science, W. Reymonta 25, 30-059 Kraków, Poland
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Abstract

The copper and copper alloys’ ingots have been subjected to structural observation in order to estimate the Peclet Number at which these ingots were solidifying. It was stated that the formation of columnar structure within the ingots occurred at a high Peclet Number, higher than the threshold value of this parameter, Pe = 500. The formulated relationships of the Growth Law correspond to a high Peclet Number due to application of the adequate development in series of the Ivantsov’s function. The Growth Law has been developed on the basis of the definition of the wavelength of perturbation which leads to the dispersion of the planar s/l interface. New definition of the index of stability connected with the behavior of solute concentration at the s/l interface has been delivered. The current definition is related to non-equilibrium solidification. The index can be easily calculated using some parameters delivered by a given Cu-X phase diagram. Physical meaning of the formulated Growth Law has also been presented.
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Authors and Affiliations

P. Kwapisiński
1
ORCID: ORCID
W. Wołczyński
2
ORCID: ORCID

  1. KGHM Polska Miedź S.A., ul. M. Skłodowskiej-Curie 48, 59-301 Lubin, Polska
  2. Institute of Metallurgy and Materials Sciences PAS, Reymonta St. 25, 30-059 Kraków, Poland
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Abstract

The suspension of copper droplets in the slag is considered. The copper/slug suspension is delivered as the product from the direct-toblister

process which is applied in the KGHM – Polska Miedź (Polish Copper) S.A. factory. The droplets / slag suspension was treated by

a special set of reagents (patented by the authors) to improve the coagulation process. On the other hand, the observations are made to

estimate if the melting / reduction process in the furnace is sufficiently effective to avoid a remaining of carbon in the copper droplets.

The coagulation process was carried out in the crucible (laboratory scale). However, conditions imposed to the coagulation / solidification

process in the laboratory scale were to some extent similar to those applied usually in the industry when the suspension is subjected to the

analogous treatment in the electric arc-furnace. Some suggestions are formulated how to improve the industrial direct-to-blister process.

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Authors and Affiliations

W. Wołczyński
A.W. Bydałek
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Abstract

The presented results of research on the effectiveness of enzymatic hydrolysis of lignocellulosic waste, depending on their initial depolymerisation in alkaline medium were considered in the context of the possibility of their further use in the fermentation media focused on the recovery of energy in the form of molecular hydrogen. The aim of this study was to determine the appropriate dose and concentration of a chemical reagent, whose efficiency would be high enough to cause decomposition of the complex, but without an excessive production of by-products which could adversely affect the progress and effectiveness of the enzymatic hydrolysis and fermentation. The effect of treatment on physical-chemical changes of homogenates’ properties such as pH, COD, the concentration of monosaccharide and total sugars and the concentration of total suspended solids and volatile suspended solids was determined. The enzymatic decomposition of lignocellulosic complex was repeatedly more efficient if the sample homogenates were subjected to an initial exposure to NaOH. The degree of conversion of complex sugars into simple sugars during enzymatic hydrolysis of homogenates pre-alkalized to pH 11.5 and 12.0 was 83.3 and 84.2% respectively, which should be sufficient for efficient hydrogen fermentation process.

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Authors and Affiliations

Marcin Wołczyński
Marta Janosz-Rajczyk
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Abstract

There are two methods to produce primary copper: hydrometallurgical and pyrometallurgical. Copper concentrates, from which copper

matte is melted, constitute the charge at melting primary copper in the pyrometallurgical process. This process consists of a few stages, of

which the basic ones are roasting and smelting. Smelting process may be bath and flash. Slag from copper production, on the end of

process contain less 0,8%. It is treat as a waste or used other field, but only in a few friction. The slag amount for waste management or

storage equaled 11 741 – 16 011 million tons in 2011. This is a serious ecological problem. The following slags were investigated: slag

originated from the primary copper production process in the flash furnace of the Outtokumpuja Company in HM Głogów 2 (Sample S2):

the same slag after the copper removal performed according the up to now technology (Sample S1): slag originated from the primary

copper production process in the flash furnace of the Outtokumpuja Company in HM Głogów 2, after the copper removal performed

according the new technology (Sample S3). In practice, all tested slags satisfy the allowance criteria of storing on the dumping grounds of

wastes other than hazardous and neutral.

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Authors and Affiliations

W. Wołczyński
M. Holtzer
A. Bydałek
A. Kmita
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Abstract

This paper presents the idea of increasing the effectiveness of slag decopperisation in an electric furnace in the "Głogów II" Copper Smelter by replacing the currently added CaCO3with a less energy-intensive technological additive. As a result of this conversion, one may expect improved parameters of the process, including process time or power consumption per cycle. The incentives to optimize the process are the benefits of increasing copper production in the company and the growing global demand for this metal. The paper also describes other factors that may have a significant impact on the optimization of the copper production process. Based on the literature analysis, a solution has been developed that improves the copper production process. The benefits of using a new technology additive primarily include increased share of copper in the alloy, reduced production costs, reduced amount of power consumed per cycle and reduced time it takes to melt. At the conclusion of the paper, the issues raised are highlighted, stressing that mastering the slag slurry process in electric furnaces requires continuous improvement.

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Authors and Affiliations

M. Wędrychowicz
W. Wołczyński
A.W. Bydałek
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Abstract

Discusses an attempt to optimize the operation of an electric furnace slag to be decopperisation suspension of the internal recycling

process for the production of copper. The paper presents a new method to recover copper from metallurgical slags in arc-resistance electric

furnace. It involves the use of alternating current for a first period reduction, constant or pulsed DC in the final stage of processing. Even

distribution of the electric field density in the final phase of melting caused to achieve an extremely low content of metallic copper in the

slag phase. They achieved by including the economic effects by reducing the time reduction.

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Authors and Affiliations

W. Wołczyński
A.W. Bydałek
S. Biernat
A. Bydałek
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Abstract

The post-processing slags containing about 0.8 wt.% of copper were subjected to the treatment of a complex reagent. The chemical composition of the complex reagent has been elaborated and patented in frame of the Grant No. PBS3/A5/45/2015. The slags had an industrial origin and were delivered by the Smelter and Refinery Plant, Głogów, as a product of the direct-to-blister technology performed in the flash furnace assisted by the arc furnace. An agglomeration of copper droplets suspended in the liquid slag, their coagulation, and deposition on the bottom of furnace were observed after the treatment this post-processing slag by the mentioned reagent. The treatment of the post-processing slags by the complex reagent was performed in the arc furnace equipped with some additional electrodes situated at the furnace bottom (additional, in comparison with the arc furnace usually applied in the Smelter and Refinery Plant, Głogów). The behaviour of the copper droplets in the liquid slag within the competition between buoyancy force and gravity was studied from the viewpoint of the required deposition of coagulated copper droplets. The applied complex reagent improves sufficiently the surface free energy of the copper droplets. In the result, the mechanical equilibrium between coagulated copper droplets and surrounding liquid slag is properly modified. Eventually, sufficiently large copper droplets are subjected to a settlement on the furnace bottom according to the requirements. The agglomeration and coagulation of the copper droplets were significantly improved by an optimized tilting of the upper electrodes and even by their rotation. Moreover, the settlement was substantially facilitated and improved by the employment of both upper and lower system of electrodes with the simultaneous substitution of the variable current by the direct current.

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Authors and Affiliations

W. Wołczyński
A.W. Bydałek
P. Migas
A. Tarasek
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Abstract

An innovative method for determining the structural zones in the large static steel ingots has been described. It is based on the

mathematical interpretation of some functions obtained due to simulation of temperature field and thermal gradient field for solidifying

massive ingot. The method is associated with the extrema of an analyzed function and with its points of inflection. Particularly, the CET

transformation is predicted as a time-consuming transition from the columnar- into equiaxed structure. The equations dealing with heat

transfer balance for the continuous casting are presented and used for the simulation of temperature field in the solidifying virtual static

brass ingot. The developed method for the prediction of structural zones formation is applied to determine these zones in the solidifying

brass static ingot. Some differences / similarities between structure formation during solidification of the steel static ingot and virtual brass

static ingot are studied. The developed method allows to predict the following structural zones: fine columnar grains zone, (FC), columnar

grains zone, (C), equiaxed grains zone, (E). The FCCT-transformation and CET-transformation are forecast as sharp transitions of the

analyzed structures. Similarities between steel static ingot morphology and that predicted for the virtual brass static ingot are described.

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Authors and Affiliations

A.A. Ivanova
B. Kania
P. Kwapisiński
W. Wołczyński

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