Pretok taline skozi keramične filtre

It is important to clean melts by filtering them with ceramic filters. Particular attention must be paid to the hydraulic conditions as the melt flows through the filter. The Bernouilli equation is used to describe the filtration of the melts. The physical regularities of the capillary melt can be seen in the flow. The Hagen-Poiseuille law and Darcy’s law have been applied. The characteristics of laminar flow have been examined, as have the attributes of turbulent flow. There are dimensionless criteria characterising the melt flow through a ceramic filter. The principal mechanisms of melt filtration are assessed.Pomembnost čiščenja kovinske taline s filtriranjem skozi keramični filter. Hidravlični pogoji pretoka taline skozi filter. Uporaba Bernouillijeve enačbe za opis filtriranja taline. Fizikalne zakonitosti kapilarnega toka taline. Hagen-Poiseuillejev in Darcyjev zakon. Značilnosti laminarnega toka. Atributi turbulentnega toka. Brezdimenzijska merila, karakteristična za pretok taline skozi keramični filter. Glavni mehanizmi filtriranja kovinskih talin

Uporaba teorije fizikalne podobnosti za opis filtriranja kovinske taline

The Bernoulli equation is the basis for the primary description of the flow of a real metallic melt through the pouring system for the filling of the casting mould with an inserted ceramic filter. In principle, a modified, dimensionless form of the Bernoulli equation can be used for the determination of the loss coefficient as a general function of the dimensionless criteria – the Reynolds, Froude and Euler numbers. It was verified by modelling the flow of the modelling liquid (in this case water) through ceramic filters. In the same interval of Reynolds numbers the loss coefficient was greater for foam filters than for filters with direct holes (strainers); however, the outlet coefficient μ of the foam filters was, in identical conditions, significantly lower than that of filters with direct holes.Bernoullijeva enačba je podlaga za opis pretoka taline skozi livni sistem z vstavljenim keramičnim filtrom. Načeloma je mogoče uporabiti modificirano brezdimenzijsko obliko Bernoullijeve enačbe za določitev koeficienta izgube kot funkcije brezdimenzijskega kriterija – Reynoldsovega, Froudovega ali Eulerjevega števila. S pretokom modelne tekočine (vode) je bilo preverjeno, da je pri enakem intervalu Reynoldsovih števil koeficient izgube večji pri penastem filtru kot pri filtru z direktnimi luknjicami, vendar pa je izhodni koeficient μ za penaste filtre pri enakih pogojih pomembno nižji kot pri filtrih z neposrednimi luknjicami

Optimisation of the slag mode in the ladle during the steel processing of secondary metallurgy

Optimisation of the slag mode in the ladle with the help of briquetted fluxing agents, based on Al2O3 under various technological conditions is the object of this paper. The aim of the industrial experiments was to assess the possibility of achieving the optimum chemical composition of the slag that would improve the kinetic conditions of the refining ladle slag during the treatment in secondary metallurgy units. Industrial experiments were focused on comparing the influences of different slag-making agents such as lime (CaO), briquetted fluxing agents and deoxidation agents forming calcium carbide (CaC2) and granular aluminium (Algranul). During the evaluation of the slag mode in the ladle, samples of the steel from different technological places under operational conditions were taken to assess the desulphurization degree. The samples of the slag for evaluating the chosen parameters, such as basicity, the content of easily reducible oxides, the proportion of CaO/Al2O3 and the Mannesmann index, were taken too. Further, the temperature and the oxygen activity in the steel were continuously measured too. The results mentioned in this paper represent the basic information about the possibilities of the slag-mode optimisation in the ladle using different proportions of the slag-making additions, briquetted fluxing agents as well as the deoxidation agents within secondary metallurgy.Web of Science47567867

Evaluation of the slag regime and desulphurization of steel with synthetic slag containing Cr2O3

The paper focuses on an evaluation of the slag regime and steel desulphurisation in a ladle with the help of synthetic slags based on Al2O3 containing various mass amounts of Cr2O3 varying from 0.3 % to 3.0 %. The aim of the plant experiments was to assess the achieved results when using two types of synthetic slag focusing on the course of desulphurisation, an analysis of the achieved chemical composition of the slag and an evaluation of the influence of oxide Cr2O3 on the increase in the chromium amounts in steel during secondary metallurgy. During the evaluation of the slag regime in the ladle, samples of steel from various technological nodes for a determination of the desulphurisation degree and the achieved chromium amounts in steel were taken. Samples of slags for the evaluation of the achieved chemical composition and amounts of Cr2O3 in the slag were also taken. The results mentioned in this paper represent the basic information about the possibilities of applying synthetic slags with increased amounts of Cr2O3 within secondary metallurgy.Web of Science4896597

Evaluation of influence of briquetted synthetic slags on slag regime and process of steel desulphurization

This paper presents the industrial results of evaluation of efficiency of synthetic slags during the treatment of steel at the equipment of the secondary metallurgy under conditions of the steel plant VÍTKOVICE HEAVY MACHINERY a.s. The aim of the heats was to assess the influence of the briquetted and sintered synthetic slags based on Al2O3 aiming the course of the steel desulphurization and slag regime during the production and treatment of steel grade 42CrMo4 with the technology EAF→LF→ VD. Within the plant experiments, basic parameters influencing the steel desulphurization and slag regime were monitored: desulphurization degree, basicity, content of easily reducible oxides, proportion of CaO/Al2O3 and Mannesmann’s index. Obtained results allowed to compare the steel desulphurization and to evaluate the slag regime. It was proved that the synthetic slag presenting the briquetted mixture of secondary corundum raw materials can adequately replace the synthetic slag created from the sintered mixture of natural raw materials.W pracy tej przedstawiono przemysłowe wyniki oceny efektywności zastosowania żużli syntetycznych podczas obróbki pozapiecowej stali w zakładzie VÍTKOVlCE HEAVY MACHINERY a.s. Celem badań był a ocena wpływu brykietówanych i spiekanych żużli syntetycznych opartych na AI2O3 - na przebieg odsiarczania stali i żużla podczas produkcji i obróbki stali 42CrMo4. zgodnie z technologią EAF → LF → VD. Podczas eksperymentów w zakładzie, monitorowano podstawowe parametry wpływające na odsiarczania stali i żużla: stopień odsiarczania, zasadowość, zawartość tlenków łatwo redukowałnych, stosunek CaO/Al2O3 oraz indeks Mannesniann’a. Uzyskane wyniki pozwoliły na porównanie stopnia odsiarczania stali w kontekście zastosowanych żużli. Wykazano, że syntetyczny żużel składający się z brykietowanej mieszaniny wtórnego korundu, może zastąpić syntetyczny żużel otrzymywany ze spieku mieszaniny surowców naturalnych.Web of Science59281380

Razvoj in preizkus nove kokile vrste 8k za ulivanje ingotov iz orodnega jekla

The traditional production of machinery and tools at ŽĎAS, a. s., and the increasing requirements placed on the final product, particularly those related to the internal quality of forgings, requires new technological measures for the ingot’s casting and solidification. The development and use of the new mould type 8K9.2 for tool-steel ingot casting has reduced the share of forgings with unacceptable quality. A substantial improvement has been achieved, especially in terms of the occurrence of defects, such as cavities and cracks in the ingot body.Tradicionalna proizvodnja strojev in orodij v podjetju ŽĎAS, a. s., in naraščajoče zahteve pri lastnostih končnega proizvoda, ki so povezane z notranjo kakovostjo izkovkov, so zahtevale nove tehnološke ukrepe pri litju in strjevanju ingotov. Razvoj in uporaba nove kokile vrste 8K9.2 za litje jeklenih ingotov sta zmanjšala delež ingotov nesprejemljive kakovosti. Pomembno izboljšanje je bilo doseženo pri pogostosti napak, razpok in votlin v notranjosti ingota

Kinetika oxidace prvků v surovém železe při jeho zkujňování kyslíkem

Import 20/04/2006Prezenční výpůjčkaVŠB - Technická univerzita Ostrava. Fakulta metalurgie a materiálového inženýrstv

Vliv doprovodných prvků na rychlost uhlíkové reakce

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