Process for the recovery of oil from waste oil sludges

A process for the recovery of oil, useful for further processing as refinery feed stock, from waste oil sludge containing oil, at least about 5% by weight solids, and a substantial amount of water, comprising:

• (a) centrifuging said sludge to substantially separate free oil and free water as a centrate from the solids,
• (b) heating solids having entrained oil and water from the centrifuging step in (a) at a temperature sufficient to volatilize all entrained oil and water, and recovering solids, said solids being classified nonhazardous by EPA toxicity test procedure,
• (c) condensing said oil and water from step (b),
• (d) centrifuging the resulting condensate from step (c) and centrate from step (a) to separate oil from water and any entrained solids,
• (e) recovering oil from said centrifuging of step (d), and
• (f) recovering water from said centrifuging of step (d), whereby said water is sufficiently clean for further treatment in a conventional water treatment facility to lower the Chemical Oxygen Demand to an acceptable limit.

A process for the recovery of oil, useful for further processing as refinery feed stock, from two or more waste oil sludges containing oil, water, and solids, at least one said sludge being fluid waste oil sludge and the other sludge being a thick waste oil sludge, comprising:

• (a) centrifuging said fluid sludge to substantially separate free oil and free water from solids and recovering the oil and water as the centrate,
• (b) heating said thick sludge and the centrifuge solids from step (a) containing oil and water at a temperature sufficient to volatilize oil and water,
• (c) condensing the oil and water from step (b) and recovering the condensate,
• (d) combining the centrate from step (a) and the condensate from step (c) and centrifuging the combined materials to separate the oil from the water, and
• (e) recovering oil from said centrifuging of step (d).

A process for the recovery of oil, useful for further processing as refinery feed stock, from waste oil sludge containing oil, solids, and a substantial amount of water, comprising:

• (a) centrifuging said sludge to substantially separate free oil and free water as centrate from solids,
• (b) passing the oil-water centrate from step (a) to a settler means,
• (c) heating the solids from the centrifuging step (a) at a temperature sufficient to volatilize entrained oil and water,
• (d) condensing said oil and water from step (c) and passing the condensate to said settler means of step (b),
• (e) centrifuging the resulting settler overflow to separate oil from water and any entrained solids, and
• (f) recovering oil from said centrifuging of step (d).

A process for the recovery of oil, useful for further processing as refinery feed stock, from waste oil sludge containing oil, solids and a substantial amount of water, comprising:

• (a) centrifuging said sludge to substantially separate free oil and free water as centrate from the sludge,
• (b) heating then resulting the sludge from the centrifuging step (a) at a temperature sufficient to volatilize entrained oil and water and leaving partially dewatered and deoiled sludge,
• (c) heating the resulting sludge from step (b) at a higher temperature than in step (b) to further volatilize oil and water from said sludge, thereby resulting in solids free of oil and water, said solids being classified nonhazardous by EPA toxicity test prodecure,
• (d) condensing said oil and water from both steps (b) and (c) and combining the condensates,
• (e) centrifuging the resulting combined condensates and said centrate to separate oil from water and any entrained solids, and
• (f) recovering oil from said centrifuging of step (e).