If implemented, the spin-off would give investors shares in a separately quoted mining finance house as part of chief executive Dieter Bock's efforts to improve shareholder value.
Lonrho Mark One would then be left running the group's extensive hotels, African food and other trading interests.
Other disposals are also on the cards, including the UK's Dutton Forshaw Motors, possibly worth pounds 50m, which takes in the Jack Barclay Rolls-Royce and Bentley distributorship.
But the market believes the group has shelved long-standing plans to hive off the hotels division, which owns the Metropole chain in the UK, Princess hotels in the US and the Caribbean, and safari lodges in Africa.
"Dieter Bock is quite pleased he didn't sell the hotels when it was first being considered. Occupancy is improving and with the Granada bid for Forte, hotel values are getting a re-rating," one market source said.
Brokers expect pre-tax profits of around pounds 150m before exceptional charges, and a dividend of up to 2.2p, when Lonrho reports on Thursday.
Rising precious metal prices, higher hotel occupancies and rationalisation are largely behind the jump from pounds 112m last time.
Lonrho shares have risen to 187p recently, valuing it at pounds 1.43bn, against the 85p paid by Mr Bock for his 18.6 per cent stake in 1993. Some analysts think the spin-off may take them past 220p, at least.
Mr Bock ousted Lonrho's founder Tiny Rowland last March and has since fought a running battle with the colourful tycoon in the courts and the press. Recently they clashed over the planned merger of Lonrho's West and East Plats mines in South Africa with rival Gencor to create the new Implats, the world's biggest platinum concern.
That deal values Lonrho's 32 per cent stake in the new Implats at pounds 400m. However, it is currently on ice while the European Commission probes effects on platinum markets. Its findings are due in May.
Mining spin-off plans are still in their early stages, but will include the new Implats holding and Lonrho's 43 per cent stake, worth pounds 480m, in the Ghanaian gold miner, Ashanti, which was hived off in 1994.
Other mining interests include coal in South Africa and gold in Zimbabwe and Uzbekistan. Hondo Oil & Gas in the US, a partnership with Amoco, may be sold separately, analysts believe.