The company ended the period with net debt of $25 million . Kerr said the balance sheet strength supports both investment in growth and shareholder returns.For the half, South32 delivered underlying EBITDA of $1.1 billion and a group operating margin of 28.2% . Underlying earnings rose to $45 million , while group free cash flow improved to $57 million , after $338 million of growth capital investment at the Hermosa project.Kerr said the company is seeing improvements in key safety measures following its gl ...