Nowadays, Web accessibility of open data is far from being guaranteed, specially for those data enthusiasts with visual disabilities because they experience barriers while accessing open data portals. In this article, we propose a Web Augmentation Framework for Accessibility for Open Data (WAFRA4OD) in order to facilitate visually-impaired users to navigate through open data portals and get the desired data easily. The main focus of this approach is the improvement of Web accessibility in open data portals using Web augmentation techniques and voice commands. Therefore, WAFRA4OD allows users to access open data through a voice interface including a set of operations: guide users to find relevant open datasets within a portal, read aloud datasets' metadata and read aloud datasets' details and contents. Therefore, by using WAFRA4OD the accessibility of open data portals is improved: data enthusiasts with visual disabilities are now able to interact with open data using voice commands. Also a case study is introduced in this article, in order to show the suitability of the WAFRA4OD proposal for data enthusiasts with visual problems such as blindness and low vision to easily access open data.