Submerged combustion melters and methods

A method of providing a molten vitrifiable material comprising the steps of:

• introducing solid batch material into a melter;
• and
• melting the solid batch material in the melter by submerged combustion in a melting chamber to provide the molten vitrifiable material within the melter as a melt having a melt surface, said melting chamber i) having a circular horizontal cross-section, ii) comprising at least five submerged burners arranged equally spaced around a substantially circular burner line, and iii) comprising a substantially cylindrical central melting zone;
• wherein during the melting step a single substantially toroidal melt flow pattern is generated in the melt of vitrifiable material, thereby allowing for a residence time in the melter whereby premature outflow of insufficiently melted or mixed batch material is reduced or avoided, said toroidal melt flow pattern comprising centrally convergent flow at the melt surface, and having a substantially vertical central axis of revolution.