The phrase "a portion of approximately" is correct and usable in written English.
It can be used when you want to indicate an estimated part or segment of something, often in contexts involving measurements or quantities.
Example: "The report indicates that a portion of approximately 30% of the budget will be allocated to marketing."
Alternatives: "an estimated part of" or "a segment of about".
When an energy developer treads that same path, however, he often sees with a kind of seismic vision, sensing beneath those same geologic sands a portion of the approximately 137 trillion cubic feet of natural gas that is believed to lie within the Rocky Mountain region.
Having emerged from bankruptcy, the revitalized company has recently reported $1.3 billion in quarterly earnings, paraded out a new chief executive and filed an initial public offering that seeks to pay back a portion of its approximately $60 billion in government loans.
Newell Rubbermaid, which is based in Atlanta, said the move is intended to permit the repayment of a portion of the approximately $750.0 million in debt that matures in the second half of 2009.
By directing a portion of the approximately $7.5 million planned program to outreach and accessibility services, the city is aiming to make families' participation quick and seamless.
A central portion of approximately 25 mg of each kidney was processed for DNA extraction at the University of East London.
A portion of this side approximately 50 m × 60 m (Fig. 1c) was selected as the target zone of this study.
A portion of Asian dust (approximately 20%) is transported to the CLP and surrounding regions by the Asian winter monsoon, while most of this dust is transported to the North Pacific Ocean (approximately 50%) via westerlies (Zhang et al. 2003).
"Section 13.14 Adjustments to Reflect Expanded Service Areas Several provisions in this License have included values reflecting the Licensee's initial Service Area represents only a portion of the City, approximately twenty-eight (28%) of the City's geography.
A portion of each transcript (approximately 10%) was reviewed for accuracy following transcription.
A portion of the strip approximately 47 mm from this tip is inserted under the tongue, and the mouth is kept closed for 2 minutes.
