METHODS OF MAKING HIGHLY PURIFIED DIATOMACEOUS EARTH WITH WIDE RANGE OF FILTRATION RATES
A highly purified diatomite composition may include greater than or equal to 90% silica, from about 0.5% to about 5% of a calcium-containing compound, and less than or equal to about 2% total of aluminum-containing oxides and iron-containing oxides. A method of making a highly purified diatomite composition may include providing a diatomite comprising at least 5% of a calcium-containing compound, calcining the diatomite, and acid washing the calcined diatomite. The calcined, acid-washed diatomite may include less than or equal to about 1% total of extractable aluminum-containing oxides and iron-containing oxides, and less than or equal to about 5% of the calcium-containing compound. The acid washing may include an acid selected from the group consisting of sulfuric acid (H 2 SO 4 ), hydrochloric acid (HCl), and nitric acid (HNO 3 ). The method may not include a flotation step.
1 . A highly purified diatomite composition comprising:
greater than or equal to 90% silica;
from about 0.5% to about 5% of a calciurn-containing compound; and
less than or equal to about 2% total of aluminum-containing oxides and iron-containing oxides.
2 . The diatomite composition of claim 1 , wherein the calcium-containing compound includes at least one of calcium oxide (CaO) and calcium carbonate (CaCO 3 ).
3 . The diatomite composition of claim 1 , wherein the diatomite composition comprises an acid-washed diatomite composition.
4 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 1% total of aluminum-containing oxides and iron-containing oxides.
5 . The diatomite composition of claim 1 , wherein the diatomite composition comprises from about 1% to about 2% of the calcium-containing compound.
6 . The diatomite composition of claim 1 , wherein the diatomite composition comprises greater than or equal to about 96% silica.
7 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 1 ppm acid-soluble arsenic.
8 . (canceled)
9 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 1 ppm acid-soluble lead.
10 . (canceled)
11 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 50 ppm acid-soluble aluminum.
12 . (canceled)
13 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 800 ppm acid-soluble soluble calcium.
14 . (canceled)
15 . (canceled)
16 . The diatomite composition of claim 1 , wherein the diatomite composition has a permeability greater than or equal to about 50 mD.
17 . (canceled)
18 . The diatomite composition of claim 1 , wherein the diatomite composition has a BET surface area greater than or equal to about 2.0 m 2 /g.
19 . (canceled)
20 . The diatomite composition of claim 1 , wherein the diatomite composition has a median particle size (d 50 ) in a range from about 5 microns to about 50 microns.
21 . (canceled)
22 . The diatomite composition of claim 1 , wherein the diatomite composition has a wet density in a range from about 0.1 to about 0.5 g/cm 3 .
23 . The diatomite composition of claim 1 , wherein the diatomite composition comprises less than or equal to about 0.5% water soluble substances as measured by the JSFA method.
24 . A method of making a highly purified diatomite composition, the method comprising:
providing a diatomite comprising at least 5% of a calcium-containing compound;
calcining the diatomite; and
acid washing the diatomite,
wherein the calcined, acid-washed diatomite comprises less than or equal to about 2% total of extractable aluminum-containing oxides and iron-containing oxides, and less than or equal to about 5% of the calcium-containing compound.
25 . The method of claim 24 , wherein the acid washing comprises washing the diatomite with at least one acid selected from the group consisting of sulfuric acid (H 2 SO 4 ), hydrochloric acid (HCl), and nitric acid (HNO 3 ).
26 . The method of claim 24 , wherein the method does not include a flotation step.
27 . The method of claim 24 , wherein the calcining step occurs prior to the acid washing step.
28 . The method of claim 24 , wherein the acid washing step occurs prior to the calcining step.
29 - 47 . (canceled)
48 . A method of making a highly purified diatomite composition, the method comprising:
providing a diatomite comprising less than or equal to about 2% of combined contents of alumina (Al 2 O 3 ) and iron oxide (Fe 2 O 3 );
calcining the diatomite; and
acid washing the calcined diatomite,
wherein the calcined, acid-washed diatomite comprises less than or equal to about 2% extractable combined alumina and iron-containing oxide