INDIRECTLY HEATABLE ROTARY KILN, USE OF A NICKEL-BASED ALLOY AND USE OF AN INDIRECTLY HEATABLE ROTARY KILN

Abstract

The invention relates to an indirectly heatable rotary kiln, the use of a nickel-based alloy, and the use of an indirectly heatable rotary kiln.

Claims

1. Indirectly heatable rotary kiln, comprising the following features: 1.1 An indirectly heatable rotary kiln tube (1); 1.2 the rotary kiln tube (1) has a nickel-based alloy coating (5) on the inside.

2. Rotary kiln according to claim 1, wherein the nickel-based alloy comprises a proportion of nickel in the range of 30-99.5%.

3. Rotary kiln according to claim 1, wherein the nickel-based alloy comprises, in addition to Ni, at least one of the following: Al, Mo or WC.

4. Rotary kiln according to claim 1, wherein the nickel-based alloy comprises a proportion of Al in the range of 0.5-20.0% and Ni in the range of 80.0-99.5%.

5. Rotary kiln according to claim 1, wherein the nickel-based alloy comprises a proportion of Mo in the range of 0.5-20.0% and Ni in the range of 80.0-99.5%.

6. Rotary kiln according to claim 1, wherein the nickel-based alloy comprises a proportion of WC in the range of 0.5-60.0% and Ni in the range of 40.0-99.5%.

7. Rotary kiln according to claim 1, wherein the coating (5) has a thickness in the range of 0.1 mm to 1.5 mm.

8. Rotary kiln according to claim 1, wherein the coating (5) is applied by at least one of the following processes: thermal spraying or baking.

9. Rotary kiln according to claim 1, comprising a metallic rotary kiln tube (1).

10. Rotary kiln according to claim 1 with a rotary kiln tube (1) made of steel.

11. Rotary kiln according to claim 1, comprising a rotary kiln tube (1) made of a heat-resistant steel.

12. Rotary kiln according to claim 1, comprising a rotary kiln tube (1) made of a heat-resistant steel.

13. Rotary kiln according to claim 1, comprising a rotary kiln tube (1) made of austenitic steel.

14. Use of a nickel-based alloy for the internal coating of an indirectly heatable rotary kiln tube of an indirectly heatable rotary kiln.

15. Use of the rotary kiln according to claim 1 for the thermal treatment of firing charge.

Description

[0044] It shows, strongly schematized and not to scale,

[0045] FIG. 1 a sectional view of a rotary kiln tube of a rotary kiln according to the invention along its longitudinal axis.

[0046] FIG. 1 shows the rotary kiln tube, designated in its entirety by the reference sign 1, of an indirectly heatable rotary kiln not shown in more detail. The rotary tube 1 has a substantially tubular shape with a longitudinal axis L. The rotary kiln tube 1 is rotatably mounted about its longitudinal axis L with a slight inclination of the longitudinal axis L with respect to the horizontal H. For this purpose, the rotary kiln tube 1 is rotatably mounted on a base via roller bearings, not shown, on which the rotary kiln tube 1 is mounted at its one, here higher end 2 and at its second, opposite, here lower end 3. The rotary kiln tube 1 consists of an austenitic steel tube 4, which has a coating of a nickel-based alloy 5 on the inside.

[0047] The rotary kiln tube 1 has a length (along the longitudinal axis L) of 2,500 mm and a clear diameter (perpendicular to the longitudinal axis L) of 186 mm.

[0048] The nickel-based alloy 5 has the following chemical composition:

Ni: 90% by mass
Al: 10% by mass.

[0049] The coating 5 has a thickness of 0.5 mm.

[0050] The difference in the coefficient of linear expansion α (at 20° with α in 10.sup.−6.Math.K.sup.−1) of the austenitic steel 4 and the nickel-based alloy 5 is less than 1.0.

[0051] To coat the austenitic steel 4 of the rotary kiln tube 1 with the nickel-based alloy 5, the nickel-based alloy 5 was applied to the inner surface of the austenitic steel 4 of the rotary kiln tube 1 by wire flame spraying.

[0052] The rotary kiln tube 1 can be indirectly heated from the outside by means of an electric heater not shown in detail.

[0053] In the practical application, the rotary kiln tube 1 is indirectly heated from the outside via the electric heater.

[0054] Furthermore, material to be thermally treated is fed into the rotary kiln tube 1 in the area of the upper end 2 via a device not shown in more detail. At the same time, the rotary kiln tube 1 is rotated about its longitudinal axis L via drive means not shown in more detail. The heating devices heat the rotary kiln tube 1 and transfer this heat to the firing charge located in the rotary kiln tube 1. At the same time, due to the rotational movement of the rotary kiln tube 1 about its longitudinal axis L, the firing charge moves towards the lower end 3 of the rotary kiln tube 1. During this passage of the firing charge through the rotary kiln tube 1, the firing charge is thermally treated in the rotary kiln tube 1. After the firing charge has passed through the rotary kiln tube 1, it is removed from the rotary kiln tube 1 by means of devices not shown in more detail.

[0055] The rotary kiln tube 1 is particularly suitable for the thermal treatment of firing charge in the form of high-quality, high-purity products, especially in the form of bulk materials, which must not be contaminated by the rotary kiln tube 1.