Jack, this Guardian article I linked to earlier is a year old but discusses those exact same figures.
It is suggested is that the old are over-represented because the figures are just for hospital admissions. Younger victims may not need as many hospital visits.

Some quotes,
"Six in 10 of all victims were male, while 71% described their ethnic origin as white British"

"Jaf Shah, the executive director of the support group Acid Survivors Trust International (ASTI), said: "Looking at the data in general, there is a fairly large probability that a high percentage of the incidents are male on male attacks and most likely to be gang related. The numbers appear to be very high and suggest an increase, which is very concerning." "

"Kwambe Ibegbuna, a social worker and community activist in Manchester, said acid attacks were becoming more common – not just among gangs but in cases of domestic violence and also for intimidation. "I've had people tell me they wanted to leave a mark, others say they were attacked because they rejected people's sexual advances. The stories vary greatly but the most consistent feature is to ensure the victim is traumatised greatly by the experience and that power has been exerted." "

There is no suggestion at all that racism is an issue.
The current case is the only one so far.
https://www.theguardian.com/uk-news/2015/sep/30/acid-attack-hospital-admissions-have-almost-doubled-in-last-10-years