UK's Vesuvius jumps after RHI Magnesita makes fourth takeover proposal

** British steel and foundry specialist Vesuvius VSVS.L up 31.1% at 491p

** On track for biggest one day pct gain since September 1990

** Company receives fourth proposal from RHI Magnesita RHIM.VI for possible offer

** Proposal values co at 551p per share, comprising 470p in cash and 0.28 new RHI Magnesita shares for every 10 Vesuvius shares

** Implies an equity value of £1.37 billion ($1.81 billion), according to Reuters calculation

** RHI Magnesita down 4.4% at 2700p

** YTD, stock is up ~2%

($1 = 0.7555 pounds)