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Seven Taphole Clay

The most eco-friendly and clean taphole clays on the market

Seven Taphole Clay

Seven Refractories is a leader in the research and development of environmentally friendly products in this sector. The strategic target in Seven’s product architecture is the engineering of the cleanest taphole clay currently possible by lowering the noxious elements contained in some raw materials.

Seven Refractories taphole clay is the answer to:

  • Daily iron production of up to 12,000 t/d
  • Short intermediate tapping tap time of 20 mins
  • Long operation on the same hole, more than 20 days
  • Easy drilling at the scheduled time, no O2
  • Long stable taphole length, > 1/3 H
  • Low plugging consumption: 3 times (r*r*π*L)
  • Long cast duration, up to 200 mins
  • Low emission into the atmosphere
  • Controlled cast rate

Cast rate, corrosion resistance and balancing the taphole wear and the renewal of the “mushroom” are all aspects creating synergy between the user’s demand and the producer’s capability.

Seven taphole clays are designed for any type of mudgun. Their bonding system has an improved temperature threshold preventing hardening in the mudgun barrel and cone.

Special attention is paid to the taphole design and manufacture to ensure stable blast furnace operation and protect the hearth walls.

Facts & Figures

The biggest and most advanced blast furnaces in the world are running on Seven Tap.

To date, more than 50 blast furnaces on four continents have been supplied with Seven’s environmentally friendly taphole clay.
The biggest furnace amounts to 4.400 m3 working volume, the most productive one to over 12.000 tons per day.

Seven takes alternative engineering routes to obtain suitable properties of the binder, in order to guarantee the lowest concentration of potentially carcinogenic compounds such as Polycyclic Aromatic Hydrocarbons (PAH). Consequently, the entire Seven tap product range has a concentration of benzo-α-pyren below 5 ppm (ten times lower than the 50 ppm danger threshold established by the German Ordinance, directly deriving from EU directive 1999/833/EC, and representing the leading guideline among environmental legislations of all EU countries).

Seven Tap Advantages

  • Resin bonded: to fully eliminate the usage of noxious tar and its derivatives from the actual product formulation.
  • Eco-friendly resin bonded: in addition to the banning of tar, a further selection of alternative raw materials pursued to minimize to traces the content of even the less dangerous volatile component.
  • High alumina raw materials: to keep high mechanical strength of the product and to make it suitable for contact with liquid metal and slag. Thus, Seven offers a refractory material fully compatible with the iron industry environment, able to perform at the highest levels of furnace productivity.
  • Top performance: an absolute must for today’s competitive world, achieved through constant research and development focused on the development of specific additives such as carbides, nitrides, and anti-oxidants. Seven’s efforts are aimed at enhancing the absolute performance of the taphole clay, but also at adapting its behavior in the different operational situations of the blast furnaces all over the world.
  • Fast curing: Speedy curing times are absolutely mandatory to guarantee the perfect holding of the closed taphole, whether in alternate casting or when running back-to-back operations in consecutive casting. The faster the curing time, the shorter the exposure of the mud-gun to the heavy conditions of the taphole face. Fast curing also enables very pushed casthouse operations with short intercasting times typical of the single-sided casting practice as the perfect holding of the closed taphole is ensured.
  • Fully customized workability: designed to adapt to different operating conditions, and to different drilling and plugging machines of various power, design and manufacturer.
  • Traceability: Each Seven Tap piece is numbered and therefore directly traceable in terms of raw materials, production process, and delivery.

Consistent product quality: a constant monitoring of the production process in several of its phases enables Seven to promptly intervene even in case of small deviations from the given targets, and steady verification of the aging with time enables the delivery of the only selected and proved material to the final customer.

Quality controls are carried out regularly in several independent laboratories to certify the lowest concentration of hazardous substances compared to products currently on the market.

All raw materials are selected and tested in our laboratories with utmost accuracy. A barcode system allows for easy and full traceability of each element in our production line.

Why are SEVEN TAP the MOST ecofriendly and clean taphole clays on the market?

Since the beginning all THC formulations of Seven Refractories have used only organic substances that do not present any danger/risk to the final user.

Some competitors have been able to reduce the level of PAH under the limit but currently none can match the Seven Tap range

Other producers have continued to use CTP or other form of pitches from fossil sources, especially in markets where environmental issues are not a topic on the environmental and health agenda

 According to REACH, none of the SEVEN TAP products are classified as dangerous.

Specific continuous monitoring systems are adopted during long transportation routes. This is essential for a material with high sensitivity to temperature, in order to better evaluate any potential stress the material undergoes during the path from production to delivery at the customer end.


Each Seven taphole clay is packed in sturdy cardboard boxes on wooden pallets, all individually PE wrapped. The packaging is specifically designed to permit stacking of up to 4 pallets, with obvious space-saving benefits in warehouse storage. The box opening system allows for easy ergonomically correct access and handling of the pieces.

Four families of products for different requirements have been designed:

Seven Tap 100 suitable for small size blast furnace
Seven Tap 200 is engineered for consistent performance in small and medium sizes blast furnaces
Seven Tap 300 a higher of raw materials with high abrasion and corrosion resistance increases the taphole performance and makes it more suitable for medium and large blast furnaces
Seven Tap 400 a high content of SiC, Si3N4 and carbon make the product suitable for big size blast furnace
Seven Tap 500 product based on SiC and Si3N4 engineered to resist to high slag rate production
Seven Tap 600 is the top grade of the range, where high purity raw materials and high content of SiC, Si3N4 and carbon make the product appropriate for big size blast furnace with high productivity