Tap-hole Clay Research Articles

The influence of binder type on the properties and performance of taphole clays for blast furnaces

Taphole clay (THC) is an unshaped refractory commonly used in blast furnaces to seal the taphole after the tapping process has been completed. THC is typically bonded with conventional coal tar pitch (CTP), but alternative binders have been developed due to the high toxicity of this material. This study investigated the performance of various binders commonly added to THCs, including CTP, phenolic novolac resin (PNR), low benzopyrene coal tar pitch (ECTP), and a petroleum-based binder (PBB). The properties of the prepared THCs were investigated, and the analytical hierarchy process was used to infer the behaviour of the prepared materials during blast furnace operation. The results obtained show that the best binder for a particular THC depends on its operational requirements. In cases where excellent injectability and hearth protection are mandatory, CTP or ECTP are highly recommended. Conversely, if a low-toxicity and easy-to-drill THC is required, PBB emerges as a promising binder. PNR is the recommended choice for blast furnaces where rapid cure and tapping stability are priorities.

Comparative study between coal tar pitch and lower polycyclic aromatic hydrocarbon (PAH) alternative binders for use in taphole clays

The use of alternative low polycyclic aromatic hydrocarbon (PAH) binders in taphole clays is essential due to health and environmental concerns associated with PAHs. Binders that could potentially substitute for highly-temperature coal tar pitch (CTPht) or coal tar (CTht) in taphole clays were investigated. These include coal tar pitch blend, low PAH coal tar pitch, petroleum-based binders and wood-based tars from various sources. The binders were characterized according to chemical composition, with an emphasis on the identification of 16-EPA-PAH (well-known carcinogens), as well as rheology and volatilization behaviour. The alternative binders were ranked according to the analytical results, with the coal tar reference binder, CTht, serving as the benchmark. Beechwood tar (Tar-BW) and crude waxy oil (CWO) showed the most favourable results for replacing CTht in taphole clay. Both have higher viscosities than CTht, lower BE-values (indicating lower toxicity), and higher degrees of mass loss over a wider temperature range.

Production of taphole clay in the conditions of JSC «DINUR»: from the idea to the development of new generation products

The production of taphole clays in the conditions of JSC «DINUR» has passed a long and problematic way during 25 years, many significant milestones have been overcome. The continuous improvement of formulas and production technology allowed the company to become the main Russian manufacturer of this type of products and to move from the concept of a unified composition to an individual approach, depending on the specific operation conditions of a particular blast furnace. Ill. 4. Tab. 1.

Improved slag resistance of taphole clay due to in situ formation of TiCN from ferrotitanium slag

To improve the slag resistance of taphole clay, we prepared it using ferrotitanium slag as raw material. TiCN was formed in situ in the taphole clay. The formation mechanism of TiCN were studied by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Results showed that TiCN can be formed by a series of reactions among CaTiO3 in the ferrotitanium slag, N2 in the atmosphere, C and Si3N4 in the taphole clay. We investigated the slag resistance of the resultant taphole clay by FESEM and compared the results with that of taphole clay prepared using brown fused alumina as a raw material. Improved slag resistance was observed in the taphole clay that used ferrotitanium slag as a raw material due to the behavior of TiCN. When the taphole clay was in contact with the molten slag at 1450 °C, TiCN was continuously distributed over the erosion interface, forming a protective layer and dispersed in the slag near the erosion interface, thus improving the slag resistance of the taphole clay.

Study of binders for ecologically safe anhydrous tap-hole clays

Detailed analytical review of the existing tap-hole clays used in the blast furnace production at various metallurgical enterprises is made. It is established that it is necessary to ensure environmental safety when using tap-hole clay. It is clarifi ed that synthetic resins (phenol-formaldehyde and novolac resins) are used instead of harmful coal-tar resin for the production of tap-hole clays. The oxidation of coal-tar resin and pitch occurs up to temperature of 600 °С, which is especially important for large blast furnaces equipped with 2...4 tap-holes.

Experimental Study on Environment Friendly Tap Hole Clay for Blast Furnace

Blast furnace (BF) is the best possible route of iron production available. Blast furnace is a high pressure vessel where iron ore is melted and liquid iron is produced. The liquid iron is tapped through the hole in Blast Furnace called tap hole. The tapped liquid metal flowing through the tap hole is plugged using a clay called tap hole clay. Tap hole clay (THC) is a unshaped refractory used to plug the tap hole. The tap hole clay extruded through the tap hole using a gun. The tap hole clay is designed to expand and plug the tap hole. The tap hole filled with clay is drilled using drill bit and the hole made through the tap hole to tap the liquid metal accumulated inside the furnace. The number of plugging and drilling varies depending on the volume of the furnace. The tap hole clay need to have certain properties to avoid problems during plugging and drilling. In the present paper tap hole clay properties in industrial use was tested and studied. The problems were identified related to tap hole clay manufacturing. Experiments were conducted in lab scale to solve the identified problems. The present composition was modified with experimental results. The properties of the modified tap hole clay were found suitable and useful for blast furnace operation with lab scale experimental results.

Studies to overcome the manufacturing problems in blast furnace tap hole clay of Integrated Steel Plants: Experimental approach

Integrated Steel Plants commonly uses Blast Furnace route for iron production which accounts for over 60 % of the world iron output. Blast Furnace runs for ten to twenty years without repairing hearth walls and Tap Hole (TH). Tap hole is an outlet for hot metal produced in a Blast Furnace and run from the shell of the furnace into the interior allowing access to the molten material. Tapping is the term used for drilling a hole through the tap hole which allows the molten iron and slag to flow out. In Iron making process, removal of liquid iron from furnace and sending it for steel making is known as cast house practice. For tapping liquid iron and operating the tap hole requires a special type of clay. Tap hole clay (THC) used to stop the flow of liquid iron and slag from the blast furnace. Present work deals with the study on manufacturing of THC at Visakhapatnam Steel Plant and problems related to manufacturing. Experiments were conducted to solve the identified problems and results are furnished in detail. The findings can improve the manufacturing process and improve the productivity of tap hole clay.

Effects of pitch addition on the properties of environmental-friendly tap-hole clay

Effects of pitch addition on the properties of environmental-friendly tap-hole clay

Comparison of 2D and 3D Computational Multiphase Fluid Flow Models of Oxygen Lancing of Pyrometallurgical Furnace Tap-Holes

Furnace tap-holes vary in design depending on the type of furnace and process involved, but they share one common trait: The tap-hole must be opened and closed periodically. In general, tap-holes are plugged with refractory clay after tapping, thereby stopping the flow of molten material. Once a furnace is ready to be tapped, drilling and/or lancing with oxygen are typically used to remove tap-hole clay from the tap-hole. Lancing with oxygen is an energy-intensive, mostly manual process, which affects the performance and longevity of the tap-hole refractory material as well as the processes inside the furnace. Computational modeling offers an opportunity to gain insight into the possible effects of oxygen lancing on various aspects of furnace operation.

Matte - tap-hole clay - refractory brick interaction in a PGM smelter

Paper written on project work carried out in partial fulfilment of BEng (Metallurgical Engineering)

Properties and Performance of a Mud Gun Mass (Tap Hole Clay) with Respect to the Stable Application of the Product in Blast Furnaces

The new generation of blast furnaces have large volumes, operate at high maximum pressures, and increased blast temperatures. This has resulted in an increase in tapping rate, tapping temperature, and the duration of tapping. This has prompted changes in relation to material and application of refractories in cast house particularly in tap hole clays. The mud gun mass is prone to early erosion and therefore to obtain a trouble free cast, a good and strong tap hole mass with appropriate physical and chemical properties is required. The main physical need is to achieve trouble free tapping of hot metal, and for there to be a constant tap hole length during the tap hole opening operation, which usually takes an hour and ten minutes. Additionally there should be smooth flow of the hot metal and slag. The delivery speed of the hot needs to be as smooth as possible. These are physical requirements to protect the hearth of the blast furnace. This paper deals with the design, performance criteria, property evaluation, and application of a mud gun mass at blast furnace tap hole sites.

SHS Ferrosilicon Nitride NITRO-FESIL®TL as a New TAP-Hole Clay Refractory Component for Blast Furnaces1

The scientific and technical manufacturing firm Etalon developed and perfected industrial technology for manufacturing SHS ferrosilicon nitride NITRO-FESIL® TL, which is a composite consisting of silicon nitride, iron silicide, and free iron. On an industrial scale together with OAO MMK and ZAO Metallurgremont test tap-hole clays are provided containing ferrosilicon nitride NITRO-FESIL® TL. Taphole clays with the new component demonstrate higher corrosion and erosion resistance, and oxidation resistance, and also better sintering capacity. As a result of this reliable sealing of iron tap-holes, a smooth, more prolonged iron and slag flow regime with stable discharge parameters is provided. The clay is recommended for introduction.

Interpretation of Tap Induced Cyclic Temperatures in the Blast Furnace Lining

AbstractThe thermal behavior of the blast furnace hearth was studied using modeling. The focus was the effect of the size and shape of the taphole clay layer around the taphole. Four different cases have been calculated: one reference case and three cases with different taphole clay layer geometries. It was found that the calculated peak‐to‐peak amplitudes of the lining temperatures during the tap cycles at the location of a thermocouple can be approximated as a linear function of the taphole clay layer thicknesses for all calculated cases. Modeling was also done where both the 90th and the 10th percentile of the observed peak‐to‐peak values of the studied tap cycles were included to describe the behavior of the operating furnace. The taphole region can be divided into three categories based on how well the model can describe the measured process data: below, at, and above taphole level. Below the taphole level, the measured lining temperature variations are smaller than for the calculated results. At the taphole level, the model can describe the behavior well. Above the taphole level the measured lining temperature variations are larger than for the calculated results. It was concluded that in order to make a more accurate heat transfer model of the taphole region, the presence of a skull build‐up below the taphole, erosion above the taphole, and the bath level variations need to be taken into account.

Effect of Si-SiC Additives on Properties of Tap Hole Clay

Non-water taphole clay was prepared by using high alumina ((Al2O3)>85%,Particle Size is 3~1, ≤1 mm),coke, clay, kyanite, Ferrosilicon Nitride Powder and Corundum powder, adding more 15% tar as the binder and Si-SiC (0,4%,8%,12%) to replace Ferrosilicon Nitride. Specimens with dimensions of φ50mm × 50mm and 125mm × 25mm × 25mm were prepared under a uniaxial pressure of 5MPa. The microstructure, high temperature bending strength (600oC,800 oC,1000 oC,1200 oC,1400 oC) and apparent porosity and sinter ability of the tap hole clay were studied. The influence of the substitution content of Si-SiC of the tap hole Clay was also investigated. The results showed that the high temperature bending strength of the samples decreased with the increasing of Si-SiC and apparent porosity almost no changing, but it could still met the need of the actual requirement. The Si-SiC substitution content within 5% of the tap hole clay has also good performance. Through the analysis of the microscopic structure of the tap hole clay, the tap hole clay with Si-SiC has good sinter ability.

Research on the Temperature Field and Roast Mechanism of Blast Furnace Tap-Hole Clay

The temperature field of blast furnace tap hole clay was analyzed by using ABAQUS software. Samples taken from the tap-hole clay in depth of 1200mm, 2200mm, 2600mm and 2800mm after roasted for 100 minutes were studied by using XRD and SEM to investigate their roast mechanism and microstructure at different temperatures. The results show that the ore phase of the tap-hole clay in depth of 1200mm remained unchanged but only tar and asphalt appear the carbonation phenomena. There is a large number of SiC crystalline phase appears in depth of 2200mm. At the same time, porosity increases and coke structure is formed. The air permeability is enhanced. In the tap-hole clay of 2600mm～2800mm depth, elongated rod-likeβ-Si3N4 grains obviously increase while the SiC grains decrease. A large number of high-temperature flocculent mullite phase appears and the high-temperature strength of the tap-hole clay is strengthened.

Investigation on the Tap-Hole Clay under Thermal Processing

Taking the waterless tap-hole clay in the 1750m3 blast furnace of Jinan Steel Corporation for example, thermal processing at temperatures ranging from 200°C to 1400°C has been performed. The authors systematically investigated the main features of the clay such as bending strength, compressive strength, porosity and density after thermal processing, the microstructure evolution of the clay with increasing temperature were also studied in brief. Research results provide theoretical information for the practical application of tap-hole clay in the blast furnace and are also helpful for understanding the possible property transition of the tap-hole clay in the tap-hole.

The effect of temperature on the extrusion behavior of a polymer/ceramic refractory paste

The effect of temperature on the extrusion behavior of a polymer/ceramic refractory paste, known as taphole clay, has been investigated. Experiments were performed to determine the extrusion pressure and the viscosity of the paste’s phenolic resin binder between 30 and 60°C. The extrusion parameters were determined using the Benbow and Bridgwater method [1]. As the temperature was increased, a decrease in the extrusion pressure was observed. Three of the four Benbow and Bridgwater extrusion parameters were found to be dependent on temperature and the binder’s viscosity. From this data a model was produced using a modified Benbow and Bridgwater equation that predicts the effect of temperature on the extrusion pressure of the paste.

The effect of storage temperatures below 100°C on the viscosity of a novolak resin propylene glycol solution

AbstractThe aging of a novolak resin solution used in iron‐making blast furnace taphole clays is reported. The novolak resin propylene glycol solution was aged at temperatures between 2 and 80°C for up to 56 days. The viscosity was measured to evaluate the change in the resin's behavior. A cure reaction was found to occur with the addition of hexamethylenetetramine (HMTA) at temperatures lower than had previously been reported. Methods for handling and storage of taphole clay to avoid excessive increases in viscosity due to aging are discussed. An approach for estimating the long term aging at temperatures of 30 to 50°C was considered using shorter term aging data obtained at 70 and 80°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 267–276, 2004