The Processing of Beach Sand from Sri Lanka for the Recovery of Titanium Using Magnetic Separation

Abstract

An investigation has been carried out to study the mineralogical and chemical characteristics of beach sand deposits from Sri Lanka and application and optimisation of different magnetic separators (induced roll magnetic separator and disc magnetic separator) to improve the recovery of titanium from the deposit. Commercial grade titanium concentrates could be achieved employing both induced roll and disc magnetic separators. However, the titanium recovery increased greatly in the magnetic fraction with a titanium content of commercial grade (up to 63.9% TiO 2 ) when paramagnetic titanium-bearing minerals were separated from beach sand using the disc magnetic separator. The results of the mineralogical and chemical analysis tests for the beach sand deposit indicated that 71% of beach sand was smaller than 355 mm in particle size and more than 99% of titanium content of the deposit was contained in this fraction.

Zirconium and hafnium

“…Heavy-mineral sand deposits in Western Australia, two deposits in India (Sattankulam and Kuttam), and one deposit in southeastern Virginia (Old Hickory) contain up to 10 percent heavy minerals (Murty and others, 2007;Zimmerman and others, 2008). In contrast, heavy-mineral sands on the northeast coast of Sri Lanka (the Pulmoddai deposit) are very high grade and contain up to 80 percent heavy minerals, including ilmenite (70 percent), zircon (8 to 10 percent), rutile (8 percent), sillimanite (1 percent) and monazite (0.3 percent); approximately 2 percent of the sand is clay sized (Premaratne and Rowson, 2003). Approximately 15 percent, by volume, of the two heavy-mineral sands deposits in India is clay sized and would be separated out and disposed of as slime (Murty and others, 2007).…”

“…The measured reserves of these two deposits are estimated to be 400 million metric tons of raw sand that covers approximately 120 km 2 (Murty and others, 2007). The amount of waste generated by these two deposits would be much greater than for the smaller (3.2 km 2 ) but higher grade deposit in Sri Lanka (Premaratne and Rowson, 2003). For another comparison, up to 50 km 2 of land could potentially be mined for heavy minerals d in the coastal plain region of the Southeastern United States (Daniels and others, 2003).…”

“…For example, slimes from the mineral-sand deposits in India contain mostly hematite, kaolinite, and quartz (Murty and others, 2007), whereas slimes from the Yoganup North Mine in Western Australia contain predominantly kaolinite (80 percent) and lesser amounts of quartz (10 percent) and goethite (10 percent) (Fujiyasu and others, 2000). Another example is the heavy-mineral sand deposit on the northeast coast of Sri Lanka, where the separation process for the concentrate generates a low-density fraction (24 percent) of quartz-rich tailings, a nonmagnetic heavy fraction (21 percent) that contains rutile and zircon, and a magnetic heavy fraction (55 percent) of mostly ilmenite and pseudorutile (Premaratne and Rowson, 2003).…”

Titanium

“…The two blocks in India cover approximately 120 square kilometers (km 2 ) and contain an estimated 400 million metric tons of raw sand and 30 million metric tons of ilmenite (Murty and others, 2007). Pulmoddai sands cover an area of only 3.2 km 2 with an even thickness of 6 m (Premaratne and Rowson, 2003); thus, the amount and type of waste generated by the two deposits in India would be very different than the waste generated at Pulmoddai.…”

“…The sands in these blocks are very homogeneous-85 percent of the sands range from <2 millimeters to 63 µm in size. Heavy-mineral sands on the northeastern coast of Sri Lanka (Pulmoddai sands) are very high grade; 71 percent of the beach sands are smaller than 355 µm, and more than 99 percent of the titanium content is in this size fraction (Premaratne and Rowson, 2003). The two blocks in India cover approximately 120 square kilometers (km 2 ) and contain an estimated 400 million metric tons of raw sand and 30 million metric tons of ilmenite (Murty and others, 2007).…”