Aluminium prices on Wednesday declined Rs 1.35 to Rs 229 per kilogram in the futures market as participants trimmed their positions on a weak trend in the spot market. On the Multi Commodity Exchange, aluminium for delivery in July fell Rs 1.35 or 0.59 per cent to Rs 229 per kg in 3,746 lots. Analysts said cutting down of positions by participants on easing demand from consuming industries mainly kept aluminium prices lower.