Sawdust has a high percentage of lignin and therefore if you want to produce paper, it is only wise to produce kraft paper using the kraft process. First of all you need to grind the sawdus a little further using a grinding machine to get finer particles. Next you boil the fine saw dust particles  for 2 hrs to remove the lignin using the following recipe:

3% NaOH (Flakes)

1% Sodium carbonate (soda ash)

0.5% Sodium sulphate

Then wash with running water to remove the black liquor.

Next bleach the slurry with double bleach system where you use both Hydrogen peroxide and sodium hypochlorite. You have to start with sodium hypochlorite first and the Hydrogen peroxide.

Recipe1:

1:1 Sodium hypochlorite for 1 hr

wash

Recipe 2:

5-8% Hydrogen peroxide

0.5% peroxide stabilizer (e.g. Clarite KA)

1% NaOH (pH 11)

Run this for 1 hr.

Wash with running water and neutralize with acetic acid (pH 6-7)

The slurry can then be used in paper making but you have to make  a certain consistency (e.g 3%), blend it in high speed stirrrer to separate the individual fibres for paper making in the wire section. initially you can try a nylon mesh to get a rough idea if it is not possible to get a fine wire mesh. During blending you can introduce softeners, plasticisers but must be anionic or non-ionic because the pulp as it were will have negative charges.

I didn't get your question. The sawdust size usually isn't proper for making paper. but if with screening the coarse size can be selected,  I think the soda pulping (with sodium hydroxide) can be a good suggestion.

If you do a web search on sawdust pulping, you will find many references.  One excellent one is: https://www.doria.fi/bitstream/handle/10024/64323/korpinen_risto.pdf?sequence=1 which discusses both commercial and laboratory issues.

Thank you for your anwers

Humphrey

I think, Pulp yield of sawdust can be lower. Because most of fibers will be damaged by chemicals. Purpose of pulping that  less damage to cellulose, more damage to lignin. If Small pieces of Wood like sawdust is using for pulp Production, yield of Pulp would be about 10-20. So Nowadays, pulp industries want raw materials which give high Pulp yield. 

Mustafa - sawdust puling has been around since the 1950's and is still being done today mostly in mills using M&D digesters and the Kraft process (some use the soda process) .  Pulp yield will vary depending on wood species but generally range from 44 - 47% for bleachable grade pulps.  This yield is lower than for wood chips (50 - 54% generally) but the lower cost of sawdust versus chips offsets the lower yield.

Thanks for your informations Dear Robert

lot of work has been done in this area by Dr. John Hatton and Dr. Martin McLoud of PAPRICAN. You can google them out, I am sure you will come across a paper which will answer your questions.