熔体处理方法对纯铝铸锭超声波除气的影响

研究了不同的熔体处理方法对纯铝铸锭超声波除气的影响,分析了影响超声波除气效果的原因.结果表明,采用合适的超声波处理,可显著地降低铸锭内的含气量.     

旋转喷吹除气装置原理及两种除气装置在应用中的对比

为了降低铝合金熔体中氢含量,提高金属纯洁度,从而提高铝合金铸锭冶金质量,我单位购置了国内外两种除气净化装置,通过合理使用,达到了满意的除气效果,保证了铸锭的,台金质量。本文研究了在线除气装置的除气净化原理,从多个方面对比了两种装置的优缺点。     

超声波处理时间对工业纯铝铸锭结晶组织的影响

研究了超声波处理时间对工业纯铝铸锭结晶组织的影响，即添加除气剂又进行超声波处理的情况。分析了超声波对工业纯铝结晶组织影响的原因。研究结果表明。采用合适的超声波处理时间，可以提高工业纯铝铸锭的细化率。     

铜液中的气体及除气

论述了铜及其合金中气体的来源及其对铸锭的危害，概括了除气、脱氧的主要方法，并对“木炭-磷”复合脱氧工艺实践进行了分析。     

铜和铜合金除气清渣熔剂的应用

1.前言无公害金属熔剂是以多盐类按比例配制而成。主要用途是在铜及铜合金熔炼过程中起覆盖、除气、清渣作用。通过除气、清渣来提高铸锭质量,最终提高加工成品率。今年4月份,六三三研究所介绍采用无公害金属熔剂。(以下简称金属熔剂)作为熔炼时的涤加剂来解决铜及铜合金铸锭中的气孔及表面缺陷,提高产品质量。这对我厂是一个极大的帮助。为了能够客观的反映该熔剂的实用性,以便于今后大批量正常生产的     

铝熔体中氢的产生机理及Alpur除气装置的除气效果

本文介绍了铝熔体中氢的产生机理以及Alpur在线除气装置的除气效果。     

一种新型铝合金熔体在线除气装置

介绍了铝合金熔体在线除气装置的作用,分析了现用在线除气装置的缺点,介绍了一种新型在线除气装置及其特点,测试了新型在线除气装置的除氢效果。     

高效紧凑型在线除气装置CDU的研制

根据最新的除气理论原理．结合生产现状研制了一种新的紧凑型在线除气装置(CDU)，该装置在只使用氩气或氮气时除气效率达50％以上。该装置体积小巧．操作维护简便．铸次间不需加热保温．放干金属约30kg。同其他同等效率的除气装置比较，其投资和运行成本分别仅为1／2～1／5和1／2～1／3。     

铸轧生产线上的除气装置

介绍铝箔铸轧生产线上铝液净化设备—除气装置的特点及其组成。该设备除气效果好，安全可靠，是铝加工产品在提高质量上的必备装置之一，可以广泛用于各铝加工厂。     

除气装置在铝锭铸造过程中的应用

本文介绍了除气装置在铸造过程中的主要作用以及常见的故障及其解决办法，并对ALPUR采用PLC的控制方式做了介绍。     

RH真空脱气动力学过程的物理模拟研究

利用ＲＨ物理模型进行了ＣＯ２从ＮａＯＨ－ＣＯ２体系中释放动力学的研究,考察了操作参数对ＲＨ脱碳和脱气反应的影响。实验结果表明脱气过程是由液相传质控制,加大提升气体流量可以加速脱气反应进行,但不同气体流量范围内影响作用有所差异。采用多孔喷吹有利于提高脱气速率,一般以４～８孔为最佳。     

Behaviour of inclusions in RH vacuum degasser

Abstract

Vacuum degassing processes are now an integral part of secondary steelmaking operations and besides the more obvious benefits of steel chemistry control to precise specifications, they also reduce the number of non-metallic inclusions. Care has to be taken, however, that the change in steel composition through loss of C, O, Mn, etc. does not result in a deleterious change in the composition of the remaining inclusions. Attempts in the past to determine the effect of vacuum on inclusion compositions have been through the use of thermodynamic models, following the inclusion engineering approach. The calculated inclusion compositions do not, however, compare well with the inclusions as analysed in samples taken from the liquid steel after the degassing operation. Clearly, it is important to take into account time dependent effects during degassing and this has been achieved by the development of a combined fluid flow-thermodynamic model. Using the computational fluid dynamics model, CFX, to establish the temperature, flow and species contours in a two-dimensional steel ladle under the influence of natural convection, the results are transferred as start conditions in a three-dimensional RH degasser model. A body force is then applied to simulate the argon bubbles that are injected into the up-leg of the degasser and changes in flow, temperature and species concentrations are calculated. Allowing for additions made during the process, the composition of the top slag and any local inclusions within the steel is predicted. The influence on top slag and inclusion chemistry of any glaze on the snorkels of the degasser is also taken into account.     

Investigation of mixing and slag layer behaviours in the RH degasser with bottom gas injection by using the VOF–DPM coupled model

The mixing time of molten steel has a decisive impact on the refining efficiency during the RH (Rheinsahl–Heraeus) degassing process. In the present work, a coupled volume of fluid method?discrete phase model has been developed to investigate the effect of bottom injection on mixing and slag layer behaviours in the RH degasser. The fluid flow, mixing characteristic, and the formation of slag eye in the RH degasser with bottom injection are well revealed. Numerical results show that X?=??0.75?m (under the up-snorkel) is the optimal injection location to obtain a shortest mixing time, as well as avoid the formation of slag eye in the RH degasser. At the same time, the result of industrial trial shows that the decarburisation efficiency can be accelerated remarkably when the bottom injection is located at X?=??0.75?m.     

RH工艺生产轴承钢脱氧和去除夹杂物研究

针对RH工艺生产w(T.O)小于0.0010%的轴承钢,通过现场试验研究了RH纯脱气时间、吹氩量和初始T.O对脱氧和去除夹杂物的影响。试验结果表明:延长RH纯脱气时间可以显著降低钢中T.O和夹杂物的数量;RH提升气体量由60m3/h增大到72m3/h,取得良好的脱氧效果;RH真空处理14min的T.O受初始T.O的影响比真空处理25min的大。     

Mathematical modelling of decarburisation and degassing during vacuum circulation refining process of molten steel: application of the model and results

The mathematical model for decarburisation and degassing in the vacuum circulation refining process of molten steel, proposed and presented earlier, has been applied to the refining process of molten steel in a multifunction RH degasser of 90 t capacity. The decarburisation and degassing processes in the degasser under the RH and RH‐KTB operating conditions have been modelled and analysed using this model. It was demonstrated that for the RH and RH‐KTB refining processes, the results predicted by the model are in good agreement with some plant data. The mean contributions of the three refining sites in six circulation cycles to decarburisation are 10.5 – 11.6, 37.4 – 38.0 and 50.5 – 52.1 % of the overall amount of decarburisation, respectively. The KTB operation can markedly accelerate the decarburisation of molten steel. Using the top blowing oxygen of 6 min with the flow rate of (600 ‐ 1000) m³(STP)/h, the initial carbon mass content of the liquid steel for the RH refining process may be increased to (550 ‐ 700) · 10‐⁴ from 400 · 10‐⁴ %. And the treatment time needed for reducing the carbon mass content in the steel to a level of ≤ 20 · 10‐⁴ % may be shortened over 3 ‐ 4 min. The effectiveness of decarburisation and degassing cannot be obviously improved by increasing the lifting argon blow rate to 900 from 600 I(STP)/min under the operating modes examined in the present work.     

超声处理对高碳钢铸锭内气孔的影响

 研究了超声处理对高碳钢铸锭内气孔的影响。研究结果表明,在1 510 ℃较低温度的高碳钢液中进行超声处理后,铸锭内产生大量气孔;增大超声波功率、提高超声处理温度、采用冷却速度相对较慢的随炉冷却方式均可以降低超声处理后铸锭中气孔率。在1 570 ℃的较高温度下,超声处理具有一定程度的脱气作用,可以明显降低高碳钢铸锭中氮的质量分数,由未经超声处理时的97×10-6降低到处理后的49×10-6。     

Numerical Simulation of Dehydrogenation of Liquid Steel in the Vacuum Tank Degasser

Vacuum tank degassers are often utilized to remove hydrogen from liquid steel. A new comprehensive numerical model, which has been developed to simulate hydrogen removal in the vacuum degassers, is presented in this paper. The degassing model consists of two sub-models, which calculate the gas-steel flow field and the species transport of hydrogen. An extended k–ε turbulence model is adopted to consider the effect of gas injection on the turbulent properties and an interfacial area concentration model is introduced to compute the interfacial area density between liquid steel and the bubbles. The fluid dynamic sub-model is validated with a physical gas stirred tank, which is believed to have similar flow phenomena as the studied vacuum degasser based on the modified Froude number. Two fundamental expressions for mass transfer coefficient, which have been paid little attention by the researchers concentrating on vacuum degassing, are evaluated with a simulation case corresponding to practical operation. The effect of vacuum pressure on the dehydrogenation process is investigated and, moreover, the integrated model is verified with industrial measurements. The predicted final hydrogen contents in liquid steel show good agreement with the measured ones. The model and the main results are presented.     

Mathematical modeling and computer simulation of the rotating impeller particle flotation process: Part II. Particle agglomeration and flotation

Effective removal of unwanted particles from a molten metal alloy by flotation relies on purging a gas into the melt through a rotating impeller. This device is commonly known as a rotary degasser. Unwanted particles in the melt attach to the rising gas bubbles and rise to the slag layer where they are removed from the metal bulk. In addition, the turbulence created by the rotating impeller causes the randomly distributed solid particles to agglomerate into relatively large clusters. These clusters float up or settle down due to the difference between their density and that of the melt. A mathematical model has been developed to describe the particle dynamics and particle agglomeration that occur during the rotary degassing of aluminum melts. While previous investigations addressed particle collisions in low intensity turbulent fields where the size of the colliding particles is smaller than the Kolmogorov length scale, this model is more encompassing as it considers both low intensity and high intensity turbulence. Consequently, this model is more representative of a typical industrial rotary degassing operation.