Method for contaminant removal in paper production
View Patent ↗The present invention relates to a process for controlling deposits in a paper making process, more particularly to a process comprising the use of talc for controlling deposits in a paper making process with talc. One aspect of the invention is contacting talc with a white water stream at one or more locations within the paper making process after separating pulp from a pulp-containing stream and before introducing the re-circulating the white water stream to one or more of a pulper, a thick-stock, a thin-stock, a dilution process, a shower, a storage vessel, a blending process, and a digestor.
1. A process for reducing depositional material in a paper making process, comprising contacting talc with a white water aqueous stream in a paper making process, wherein the white water aqueous stream comprises less than about 5 wt % solids such that the white water aqueous stream has a long fiber content less than about 5 wt %, wherein the talc is contacted with the white water aqueous stream after a high shear event, the high shear event resulting in formation of one or more free fatty acids, wherein the one or more free fatty acids are adsorbed by the talc.
2. The process of claim 1 , wherein contacting the talc with the aqueous stream forms a depositional material-loaded talc and a depositional material-depleted aqueous stream, and wherein the depositional material-depleted aqueous stream has at least about 10 % less depositional material than the aqueous stream.
3. The process of claim 1 , further comprising:
forming the aqueous stream by separating wood pulp from a wood pulp-containing aqueous stream.
4. The process of claim 1 , wherein the talc is contacted with the aqueous stream at a location where the aqueous stream has a Reynolds number of at least about 2200.
5. The process of claim 1 , wherein the talc is in the form of an aqueous dispersion.
6. The process of claim 1 , wherein the talc has a median particle size from about 2 to about 5 microns.
7. The process of claim 1 , wherein the white water aqueous stream contains less than about 2 wt % solids.
8. The process of claim 1 , wherein from about 1 to about 100 lbs. of the talc are contacted with the white water aqueous stream for about each ton of solids in a fiber-containing pulp of the papermaking process.
9. The process of claim 1 , further comprising, after contacting the talc with the white water aqueous stream, circulating the white water aqueous stream to another portion of the paper making process.
10. The process of claim 1 , wherein the size of the one or more free fatty acids is less than 0.5 microns.
11. The process of claim 1 , wherein the size of the one or more free fatty acids is less than 0.1 micron.
12. The process of claim 1 , wherein the size of the one or more free fatty acids is less than 0.01 micron.
13. The process of claim 1 , wherein the size of the one or more free fatty acids is less than 0.001 micron.
14. The process of claim 1 , wherein the amount of at least one of the one or more free fatty acids after the step of contacting is less than 10,000 ppm.
15. A process for reducing depositional material in a paper making process, comprising separating pulp from a pulp-containing stream to form a re-circulating white water stream and adding talc to the re-circulating white water stream before introducing the re-circulating white water stream to a stream having a pulp content higher than the pulp content of the re-circulating white water stream,
wherein the talc is contacted with the re-circulating white water stream after a high shear event, the high shear event resulting in formation of one or more free fatty acids, wherein the one or more free fatty acids are adsorbed by the talc.
16. A process for making paper products, comprising:
a) contacting a wood based fiber-containing material with water to form a woody fiber-containing stream;
b) contacting the woody fiber-containing stream with a pulp-retention device to form a wet paper sheet and a white water;
c) drying the wet paper sheet to form a dry paper sheet;
d) contacting the white water with talc to form a talc-containing white water; and
e) circulating at least a portion of the talc-containing white water with the woody fiber-containing stream, wherein the white water is contacted with the talc after the pulp-retention device and before said circulating,
wherein the talc is contacted with the white water after a high shear event, the high shear event resulting in formation of one or more free fatty acids in the white water,
wherein the one or more free fatty acids are adsorbed by the talc, and
wherein the one or more free fatty acids are at least one of an emulsion and a dispersion of depositional material.
17. The process of claim 16 , wherein after contacting the talc with the white water a fatty acid composition within the white water is absorbed onto the talc such that free fatty acid in the white water is reduced by at least about 10 wt %.
18. The process of claim 16 , wherein contacting the talc with the white water results in adsorption of the depositional material onto the talc, thereby reducing the free the depositional material content of the white water by at least about 10 wt %.
19. The process of claim 16 , wherein the talc is contacted with the white water at least during the forming of the white water in step b).
20. The process of claim 19 , wherein the talc comprises an aqueous dispersion.
21. The process of claim 16 , wherein the talc is contacted with the white water within about 10 minutes after forming of the white water in step b).
22. The process of claim 16 , wherein the talc has a median particle size from about 2 to about 5 microns.
23. The process of claim 16 , wherein the white water contains less than about 2 wt % solids.
24. The process of claim 16 , wherein from about 1 to about 100 lbs. of the talc are added to the white water for about each ton of solids contained within the woody fiber-containing stream.