422 JOSEPH STRUTHERS 



pure. The purified crystals of borax are removed from the 

 vats, washed free from adhering mother Uquor, dried, ground, 

 and screened into several grades for the market. 



At the Marion (Cal.) works the crude colemanite ore is 

 submitted to a concentration, and the rich concentrates are 

 shipped to the refinery at Bayonne, N. J., for final conversion 

 into borax. These concentrates are in two forms, lumps and 

 fines. Formerly the low grade ores at Marion were rejected, 

 but at the present time they are heated in a two-hearth, 100- 

 ton Holthoff-Wethey furnace, fired by six oil burners. A 

 gentle heat suffices to cause the colemanite m the ore to disin- 

 tegrate physically into a sand like product called flour, which 

 is removed when cold by screening, and is sacked and shipped 

 to the Bayonne refinery. One disadvantage of the separa- 

 tion of the colemanite by heating in a furnace is that any 

 pandermite (the compact variety of the mineral) present in 

 the ore is not affected by the heat, and is consequently left in 

 the waste material remaining in the screens. At times the 

 waste equals in quantity one half of the flour product. 



The conversion of the colemanite into borax at the Bay- 

 onne refinery in New Jersey is made by decomposing the calci- 

 um borate with sodium carbonate, leaching out the sodium 

 biborate with water, yielding a solution which is separated 

 from the insoluble calcium carbonate by passage through a 

 filter press at a pressure of from 50 to 100 pounds per square 

 inch. The clarified solution is transferred to vats having wires 

 suspended from 2-inch iron pipes extending across the top of 

 the vat. The crystals of borax form on these wires as well as 

 on the sides and bottom of the vat, those on the wires being 

 sufficiently pure for all trade requirements, while those on the 

 sides and bottom of the vat have to be redissolved and puri- 

 fied by a second crystallization. The pure crystals are crushed, 

 screened, and sorted into three grades— refined crystals, re- 

 fined screenings, and granulated borax. The crystals and 

 screenings are packed for the market, but the granulated borax 

 before shipment undergoes a final treatment, which consists 

 of heating in an inclined rotating cylindrical furnace, crushing 

 to the fineness of flour in a pulverizer, settling and collecting 



