Slurry of manganomanganic oxide particles and method for the production of slurry
A stable non-settling slurry of water and manganomanganic oxide particles having a particle size below 10 μm. The slurry comprises water and up to 92 wt % manganomanganic oxide particles bade on the weight of the slurry. The slurry has a pH between 9 and 11 and contains 0.05 to 0.5 wt % of a dispersant based on the weight of dry manganomanganic oxide particles. The dispersant can be an ethoxylated polycarboxylate or a polyacrylic acid salt and has a molecular weight between 500 and 50 000 g/mol.
1. A stable, non-settling slurry comprising:
water;
manganomanganic oxide particles having a particle size below 10 μm, the manganomanganic oxide particles present in the slurry in an amount up to 92 wt % based on the weight of the slurry;
a dispersant in an amount of 0.05 to 0.5 wt % based on the weight of dry manganomanganic oxide particles in the slurry, the dispersant having a molecular weight between 500 and 50,000 g/mol and selected from an ethoxylated polycarboxylate and a polyacrylic acid salt; and
a ph of the slurry being 9 to 11.
2. The slurry of claim 1 , wherein the amount of the manganomanganic particles present in the slurry is greater than 80 wt % based on the weight of the slurry.
3. The slurry of claim 1 , wherein the amount of the dispersant is 0.07 to 0.15 wt % based on the weight of dry manganomanganic oxide particles.
4. The slurry of claim 1 , wherein:
the dispersant is a polyacrylic sodium salt having a molecular weight of about 3000 g/mol.
5. The slurry of claim 1 , wherein:
the dispersant is an ethoxylated polycarboxylate; with a hydrophobic chain as a side chain.
6. The slurry of claim 1 , wherein:
the ethoxylated polycarboxylate has a molecular weight of about 20,000 g/mol.
7. The slurry of claim 1 , wherein:
the ph of the slurry is 9.5 to 10.5.
8. The slurry of claim 1 , wherein the ph of the slurry is adjusted using sodium hydroxide.
9. A method of producing a stable, non-settling aqueous slurry of manganomanganic oxide, comprising:
Mixing manganomanganic oxide particles, water and a dispersant to form a slurry, wherein the manganomanganic oxide particles have a particle size below 10 and are presentin an amount up to 92 wt % based on the weight of the slurry, the dispersant is present in an amount of 0.05 to 0.5 wt % based on the weight of the dry manganoanganic oxide particles present in the slurry, the dispersant is selected from an ethoxylated polycarboxylate and a polyacrylic acid salt; and the dispersant has a molecular weight of 500 to 50,000 g/mol; and
adjusting the ph of the slurry from 9 to 11.
10. The method of claim 9 , wherein:
first, dispersant is added and mixed with the water;
second, sodium hydroxide is added and mixed with the dispersant and water mixture;
third, the manganomanganic oxide particles are added and mixed with the water, dispersant and sodium hydroxide mixture at a low rate of mixing;
fourth, after adding all of the manganomanganic oxide particles to the water, dispersant and sodium hydroxide mixture, a high rate of shear is applied to the water, dispersant, sodium hydroxide and manganomanganic oxide particle mixture to form the slurry.
11. The method of claim 9 wherein:
the ph of the slurry is adjusted with sodium hydroxide.
12. The method of claim 9 , further comprising:
pumping the slurry through a sieve system to remove coarse particles having a diameter greater than 45 μm from the slurry, after the slurry has been prepared.
13. An oil well cement composition comprising cement powder, water and the slurry of claim 1 .