Four Teenagers Jailed for Torture
They all pleaded guilty to causing grievous bodily harm.
They also all admitted attempting to pervert the cause of justice.
Flame throwers
The two males cannot be considered for parole until they have served at least three years and three months.
Worcester Crown Court heard the attack took place at Darkes and Smales' flat in Burcot Lane on 23 March.
Prosecuting, Nicholas Cartwright said Miss James was also verbally abused, threatened with a knife, battered with a chair and foot-rest.
Her ordeal lasted for many hours and amounted to torture, physical and mental cruelty ~Judge Alastair McCreath
She was forced to drink a glass containing urine and cigarette butts and made to eat chilli powder.
Her hair and head were burnt when two aerosols were converted into "flame-throwers".
He said Kirby instigated the violence claiming to have suffered a miscarriage because Miss James smoked near her.
Judge Alastair McCreath called their behaviour "unspeakable and wicked".
"Her ordeal lasted for many hours and amounted in ordinary language to torture, physical and mental," he said.
"Whatever the apparent reason for it was, what you did was grotesquely out of proportion to anything she had ever done to you, if she had ever done anything at all."
Hearing problems
Katy's mother, Dawn Lazri, said the attack had left her daughter with long-term problems.
"She has severe scarring to her stomach and legs, on which she hopes to have plastic surgery at some time in the future.
"In addition, she now has hearing problems which were caused by the blows inflicted to her head, and she suffers from a lack of confidence."
Det Sgt Sue Farrell, from Bromsgrove CID, said it was a nasty attack which caused shock in the community.
"Katy was lucky in that her injuries were not even more serious.
"However, an experience like this is not easily forgotten.
"We are keen to reassure residents that incidents of this nature are extremely rare."