The phrase "amalgamated into a single" is correct and usable in written English.
It can be used when describing the process of combining multiple elements into one cohesive unit.
Example: "The various departments were amalgamated into a single entity to improve efficiency."
Alternatives: "merged into one" or "consolidated into a single".
In all, the amendment comprises five sections, four of which began in 1866 as separate proposals that stalled in legislative process and were amalgamated into a single amendment.
Canadian progressives outnumber conservatives almost two to one but the country has had eight years of conservative government because, while the right-wing parties amalgamated into a single Conservative party in 2003, the vote on the left is split between two major parties – the Liberals and the NDP – and a few minor ones, including the Greens.
In this way, all suboptimal fitness individuals are amalgamated into a single "mutant" class.
The channel that existed between the two ridge-shaped nuclei has been infilled by the progradation: the two ridges have become amalgamated into a single large tidal bar.
While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer (LGT) or alternatively out-competed by our putatively more evolutionarily robust form of life.
The Cilgwyn quarries were taken over by a company in 1800, and the scattered workings at all three locations were amalgamated into a single quarry.
This process inevitably led to similar suggestions being amalgamated into a summary question that was broader in scope than the individual suggestions contributing to it.
Even his evil deeds, never forgotten, have been somehow amalgamated into a memory of greatness.
From the late 1810s, the Sotho peoples amalgamated into a defensive state under the leadership of Moshoeshoe, particularly after the Boer invasions (the Great Trek) of the mid-1830s.
A being endowed with a sense of sight and presented with a variously coloured panorama would not experience all the different colours to be amalgamated into a point.
