International Standard MgO Content % ZSA-65 Zirconia Brick for Glass Furnace Crown Foot

 High quality Zirconia Brick ZSA-65 

Zirconia Brick ZSA-65 is a refractory brick with zircon as the main phase and is one of the important varieties of zirconium-containing refractories.

(1) Treatment of raw materials of Zirconia Brick ZSA-65.

The raw material of the Zirconia Brick ZSA-65 is a selected zircon ore, referred to as zircon sand. It contains about 90% zircon. The zircon concentrate sand has a fine particle size and is single, generally 0.1-0.2 mm. It is not suitable to directly make refractory bricks.

In order to prepare the pure Zirconia Brick ZSA-65 with coarse particles, in order to adjust the particle size composition of the refractory brick and reduce the firing shrinkage, the zircon clinker agglomerate is usually prepared by pre-calcining or high-temperature melting of the concentrate sand. When calcining the clinker, firstly grind a part of the concentrate sand into fine powder, mix it with another part of the concentrate sand, and bond it with a temporary organic binder to make the ball or waste, at 1500-1700 ° C (below the decomposition of zircon) Calcined into dense agglomerates at temperature). If an alkali metal oxide or a mineralizer such as MgO or CaO is present, it may be calcined at a lower temperature of 1050 ° C or higher. Zircon sands shrink from 900 ° C at the time of calcination, shrinkage tends to stop at about 1350 ° C, and then expands, and then shrinks sharply after 1700 ° C. The zircon concentrate sand mass is improved in compactness after calcination, and the bulk density can reach 3.5g/cm3 or more. If pure Zirconia Brick ZSA-65s are produced from fine powder, the concentrate sand can be directly calcined at 1450 ° C, quenched by quenching, and then ground.

(2) Production of Zirconia Brick ZSA-65.

Temporary binders such as sulfite pulp waste, dextrin and lignin should be used in the production of pure Zirconia Brick ZSA-65s. Ethyl silicate, calcium alkylate and phosphoric acid, and water glass can also be used. If a plastic refractory clay is used as a binder, the refractory brick is easy to form and sinter, but it tends to cause a decrease in the refractoriness and volume stability of the refractory brick. Especially when the amount of clay added to the ingredients is high, the effect is particularly significant. In order to promote the sintering of pure Zirconia Brick ZSA-65s, a small amount of CaO or Ca(OH)2, MgO or MgF2 and other mineralizers are often added to the ingredients. This admixture promotes the decomposition of ZrO2·SiO2 at high temperatures and forms a ZrO2 solid solution with ZrO2 and enters the glass phase to promote sintering.

When blending with pure zircon, in order to ensure good properties and precise shape of the refractory brick, the particle size, the amount of the binder and the amount of the admixture must be precisely matched. For refractory bricks containing coarse particles of various levels, multi-stage particle batching is required, and the specific surface area and content of the fine dressing should be higher than that of ordinary refractory bricks, so as to facilitate the formation of a dense green body and facilitate sintering. If the body is composed entirely of fine particles, the maximum particle size of the fine powder is usually 44/μm or less, and a few micrometers should be majority. When molding, according to the requirements of the density of refractory bricks, ordinary refractory bricks are generally formed by the method of squeezing and dry pressing; the dense ones are mostly mud-casting; the high-density is commonly used for mud casting and isostatic pressing. The various components in the furnish should correspond to the forming method. This pure Zirconia Brick ZSA-65 must be fired at a higher temperature. High-density refractory bricks need higher temperature. According to the nature and content of fine powder in the green body and the type and quantity of mineralizer, the highest firing temperature is generally around 1700 °C, which should be controlled in the sintering of the green body without significant deformation. At the temperature and corresponding to the holding time.

Technical datas of Zirconia Brick ZSA-65

Performance of Zirconia Brick ZSA-65

In industrial production, in order to reduce costs and improve economic efficiency, Zirconia Brick ZSA-65 have been widely used in the manufacture of Zirconia Brick ZSA-65. The crystal of zircon (ZrSiO4) is a tetragonal crystal, and the crystal form is usually in the shape of a quadrangular prism. The colors are reddish purple, brown, yellow, gray, and the like. The theoretical composition of zircon is ZrO2: 67.23%, SiO2: 32.77%. Zircon has a melting point of 2420 ° C, a density of 4.6 to 4.7 g/cm 3 and a Mohs hardness of 7.5.

The zircon raw material used for the manufacture of Zirconia Brick ZSA-65s requires a purity of 98% to 99%, wherein the content of ZrO2 should be greater than 63%, and the lower the impurity content, the better. When manufacturing a product, the pure zircon fine powder is first pressed into a compact, calcined at about 1600 ° C, then crushed, molded, and finally fired. Zircon is slowly dissociated from 1540 ° C, and dissociates rapidly from 1750 ° C. At 1870 ° C, the dissociation amount reaches 95%, and the dissociation products are monoclinic zirconia and silica glass. As the dissociation progresses, the variant expansion of zirconia also gradually becomes significant. Due to this feature, the final firing temperature of Zirconia Brick ZSA-65s does not exceed 1600 °C. According to the volume change of the zircon body during the firing process, the temperature rise rate below 600 ° C should be slow to facilitate the removal of moisture and organic matter in the body; between 600 and 1200 ° C, sintering has not yet begun. The temperature rise can be accelerated. Between 1200 and 1500 ° C, the green body undergoes severe shrinkage, so the heating rate should be slow. When molding Zirconia Brick ZSA-65s by molding, it is necessary to add appropriate flux and mineralizer. An example of the ingredients is: 40% fused zircon pellets, 40% zircon sand, 20% zircon powder, and a small amount of fluoride. Using dextrin as a binder, it is molded under high pressure. 

Because zircon is cheaper than zirconia, and it is easy to obtain natural raw materials, it does not change in structure, has low linear expansion coefficient and good thermal shock resistance, so it is a valuable refractory material. The Zirconia Brick ZSA-65 can be used as a crucible for smelting lead, antimony and other metals and alloys thereof, cast steel ladle lining bricks, nozzle bricks, and containers for melting alkali-free glass and molten pool bricks.

Workshop corner

 Packing of Zirconia Brick ZSA-65

 Shipping of Zirconia Brick ZSA-65

1.Our packaging is as per customer’s request
2.Normal goods delivered by sea transport
3.Sample shipping by express
4.We will shipping and delivery goods timely, quanlity and quantity guaranteed, and also in accordance with the contract and customer's requirment completely.

1. Strong professional:
Our company has thirty years producing experience in refractory products. Our manager will supervise on a various refractorys production materials, process control, quality supervision and package delivery, and ensure the products are 100% qualified.

2.Annual supply:
Our company has passed ISO9001 quality management system certification and SGS certification. And the annual supply of shaped and unshaped refractory product is 28, 800-35, 000 tons.

3. Export experiences:
Now we have gained a global sales network reaching Taiwan, Russia, Vietnam, Pakistan, Bulgaria, French, India, Congo, Angola, South Africa, and so on.

4. Production equipment:
Production and testing equipments are new, complete and automated or semi- automated. Such modern facilities and equipments have provided the fine technical guarantee for the production and testing.

5. Testing equipment:
Our company's testing equipments as follows:
High Temperature RUL Tester
Bulk Density Tester
The Pressure Tester
Refractoriness Tester

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