Refractory product, a batch for producing the product, a method for the production of the product and a use of the product

A refractory product comprising the following features:

• the refractory product has a chemical composition according to which the following oxides are present in the following proportions:
• MgO:
• at least 92% by mass;
• Al2O3:
• 1.5 to 7% by mass;
• Fe2O3:
• less than 3% by mass;
• CaO+SiO2:
• 1 to 3% by mass;
• the refractory product comprises coated grains having the following features:
• the coated grains have a grain size of at least 2 mm;
• the coated grains consist of magnesia, the surface of which has a coating of magnesia spinel at least in sections;
• and
• the coating of magnesia spinel having a thickness in the range from 10 to 500 μm, wherein the refractory product is produced based upon a batch comprising the following features:
• a first raw material component, consisting of grains of magnesia;
• a second raw material component, consisting of batch coated grains, comprising the following features:
• the batch coated grains have a grain size of at least 2 mm;
• the batch coated grains consist of magnesia, the surface of which has a coating of alumina at least in sections.

A method for the production of a product comprising the following steps:

• providing a batch, where the batch is for producing a refractory product, the batch comprising the following components:
• a first raw material component, consisting of grains of magnesia;
• a second raw material component, consisting of coated grains, comprising the following features:
• the coated grains have a grain size of at least 2 mm;
• the coated grains consist of magnesia, the surface of which has a coating of alumina at least in sections;
• shaping the batch into a shaped unfired refractory product;
• firing the shaped unfired refractory product into a shaped fired refractory ceramic product, the shaped fired refractory product comprises the following features:
• the shaped fired refractory ceramic product has a chemical composition according to which the following oxides are present in the following proportions:
• MgO:
• at least 92% by mass;
• Al2O3:
• 1.5 to 7% by mass;
• Fe2O3:
• less than 3% by mass;
• CaO+SiO2:
• 1 to 3% by mass;
• the shaped fired refractory ceramic product comprises the coated grains having the following features:
• the coated grains have a grain size of at least 2 mm;
• the coated grains consist of magnesia, the surface of which has a coating of magnesia spinel at least in sections;
• and
• the coating of magnesia spinel having a thickness in the range from 10 to 500 μm.

A method comprising:

• using a refractory product for lining of cement rotary kilns, where the refractory product comprises the following features:
• the refractory product has a chemical composition according to which the following oxides are present in the following proportions:
• MgO:
• at least 92% by mass;
• Al2O3:
• 1.5 to 7% by mass;
• Fe2O3:
• less than 3% by mass;
• CaO+SiO2:
• 1 to 3% by mass;
• the refractory product comprises coated grains having the following features:
• the coated grains have a grain size of at least 2 mm;
• the coated grains consist of magnesia, the surface of which has a coating of magnesia spinel at least in sections;
• and
• the coating of magnesia spinel having a thickness in the range from 10 to 500 μm.