S11D (also known as Serra Sul) is a large surface mine being developed by Vale in the state of Pará, Brazil. The project is approximately 60 kilometres southwest of Vale's largest operating mine, Serra Norte. S11D is one of the largest undeveloped resources of high-grade, direct shipping iron ore known in the world. The mine produces a sinter feed fines product which is entirely sold into the seaborne export market. Output from the operation is shipped through Vale's EFC rail line to the Ponta da Madeira terminal at Itaqui port, in the state of Maranhão. In 2018, Vale announced an expansion project at S11D which reinforces the company's strategy to increase the share of high-grade products within its sales portfolio. S11D's costs place it at the bottom of the industry cost curve. Low operating costs are due to the project's low-strip, high-grade reserves and a truckless mining system.