Forward osmosis process for concentration of lithium containing solutions

A forward osmosis process for concentration of lithium-containing salt solutions is described. A difference in osmotic pressure between a lithium-containing salt solution and a second salt solution of higher osmotic pressure is used as a driving force to pass water through a semi-permeable forward osmosis membrane from said lithium-containing salt solution of lower osmotic pressure to the salt solution of higher osmotic pressure. Also, a two-part operation is described wherein reverse osmosis process technology and forward osmosis process technology are used in tandem to concentrate lithium-containing salt solutions and to recover water that can be recycled to the process. The forward osmosis process is conducted without requiring (i) use of superatmospheric pressure or (ii) use of subatmospheric pressure or (iii) use of both such pressures, or (iv) use of one or more additives to assist in causing the flow of water through a forward osmosis membrane.