Core for proppant and process for its production

1 . A core which is formed from a raw material mixture comprising at least a solid powder resin and a further finely divided starting material, and which, in the thermally treated state, has a density of less than 2 g/cm 3 .

2 . The core of claim 1 wherein the starting material is comprises finely divided rock flour or glass flour.

3 . The core of claim 1 wherein the starting material comprises ash or dusts from thermal processes.

4 . The core of claim 1 , wherein the raw material mixture includes, as a further starting material, organic materials, preferably wood dusts, cereal flours and/or polymer dusts.

5 . The core of claim 1 , wherein the starting material further includes fibrous materials.

6 . The core of claim 1 , wherein the raw material mixture further includes organic or inorganic binders.

7 . The core of claim 1 having a particle size of 0.2 mm to 2 mm.

8 . The core of claim 1 further comprising a a coating comprising inorganic organic material.

9 . The core of claim 1 further comprising an impregnation.

10 . (canceled)

11 . A process for producing the core of claim 1 comprising mixing the raw material components to form a raw material mixture and granulating to form cores then subjecting the cores to a thermal treatment in the temperature range of about 120° C. about 220° C.

12 . A process for producing the core of claim 1 comprising mixing the raw material components to form a raw material mixture and conditioning at the same time to form a suspension, then spraying the suspension into a thermal reactor then subjecting the cores to a thermal treatment.

13 . The process of claim 11 further comprising adding a liquid medium before, during or after the mixing.

14 . The process of claim 11 further comprising adding liquid or solid assistants before, during or after the mixing.

15 . The process of claim 11 further comprising adding further starting materials before or during the granulation or the suspension, wherein the further starting materials are liquid or solid organic material.

16 . The process of claim 11 further comprising adding further starting materials before or during the granulation or the suspension, wherein the further starting materials are fibrous materials.

17 . The process of claim 11 further comprising adding particle seeds of hardened cores before or during the granulation or the suspension.

18 . The process of claim 11 further comprising adding binders, before or during the granulation or the suspension.

19 . The process of claim 11 further comprising utilizing a separating agent.

20 . The process of claim 1 wherein the cores are powdered with the separating agent before the thermal treatment.

21 . The process of claim 19 wherein the separating agent is blown in during the thermal treatment.

22 . The process of claim 11 wherein the thermal treatment takes place in a countercurrent rotary tube oven which is heated directly or indirectly.

23 . The process of claim 11 wherein the thermal treatment takes place in a drier.

24 . The process of claim 1 wherein the thermal treatment takes place in a fluidized bed.

25 . The process of claim 12 wherein the thermal treatment, dries and completely hardens the powder resin.

26 . The process of claim 12 wherein the thermal treatment, only partially hardens the powder resin.

27 . The process of claim 26 wherein a subsequent thermal treatment completes the hardening of the powder resin.

28 . The process of claim 11 further comprising coating or impregnating the cores.

29 . The process of claim 28 wherein the coating or impregnation is effected separately after the core production.

30 . The process of claim 28 wherein the coating or impregnation is effected during the core production in a cooling process.